Crispy Onion Chicken Sandwich

Featured in: Weekend Homestyle Favorites

This mouthwatering sandwich combines buttermilk-marinated chicken thighs fried until golden and crispy, layered with homemade crispy fried onions and creamy garlic aioli on a soft brioche bun. The preparation involves marinating the chicken for flavor depth, carefully breading and frying both the chicken and onions to achieve maximum crunch, and blending a simple aioli for creaminess. Perfect for a satisfying main dish that serves four, ready in under an hour with medium-level cooking skills.

Updated on Sun, 18 Jan 2026 12:20:00 GMT
Golden-brown Crispy Onion Chicken Sandwich on a toasted brioche bun, piled high with crunchy fried onions and creamy aioli.  Pin It
Golden-brown Crispy Onion Chicken Sandwich on a toasted brioche bun, piled high with crunchy fried onions and creamy aioli. | sweetcairn.com

The sizzle of chicken hitting hot oil always takes me back to a crowded food truck festival where I first tasted a sandwich that made me stop mid-conversation. Golden fried chicken piled high with crispy onions, dripping with garlicky aioli, all squeezed into a buttery bun that barely contained the chaos. I went home that night determined to crack the code. After a few flour-dusted kitchen experiments and one slightly burnt batch of onions, I finally nailed it, and now this sandwich is my go-to whenever I want to impress someone or just treat myself to something ridiculously satisfying.

I made these sandwiches for my brother's birthday last summer, and he declared it better than any restaurant version he'd ever tried. We sat on the back porch with paper towels piled high, laughing as aioli dripped down our fingers and crispy onion shards fell onto our plates. My sister-in-law asked for the recipe three times before we even finished eating. It became clear that day: this wasn't just a sandwich, it was the kind of food that turns a regular afternoon into a memory.

Ingredients

  • Boneless, skinless chicken thighs: Thighs stay juicy and forgiving even if you slightly overcook them, plus they have more flavor than breasts.
  • Buttermilk: The acidity tenderizes the meat and adds a subtle tang that balances the richness of frying.
  • Garlic powder and paprika: These build a savory base in both the marinade and breading, layering flavor at every step.
  • All-purpose flour and cornstarch: The cornstarch makes the coating extra crispy and light, not heavy or doughy.
  • Smoked paprika: A little smokiness in the breading adds depth without overpowering the chicken.
  • Yellow onion: Thinly sliced and fried until golden, they become sweet, crunchy, and almost addictive.
  • Mayonnaise: The creamy base of the aioli that clings to every surface and ties all the textures together.
  • Garlic clove and lemon juice: Fresh garlic and a squeeze of lemon brighten the aioli and cut through the fried richness.
  • Dijon mustard: Just a touch adds a gentle tang and helps emulsify the aioli.
  • Brioche buns: Soft, slightly sweet, and sturdy enough to hold all the fillings without falling apart.

Instructions

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Marinate the Chicken:
Whisk together buttermilk, garlic powder, paprika, salt, and black pepper in a bowl, then submerge the chicken thighs completely. Cover and refrigerate for at least 30 minutes, or up to 4 hours if you have time.
Prepare the Breading:
In a shallow dish, combine flour, cornstarch, smoked paprika, salt, and black pepper, mixing well. This dry mixture will create that irresistible crunch.
Coat the Onions:
Toss thinly sliced onions with flour, salt, and black pepper until every piece is lightly dusted. Shake off any excess so they fry up crisp, not clumpy.
Fry the Onions:
Heat about 1 inch of vegetable oil in a large skillet to 350°F, then fry the onions in batches for 2 to 3 minutes until golden and crispy. Drain them on paper towels and resist the urge to snack on them all before assembly.
Bread and Fry the Chicken:
Remove chicken from the marinade, let excess buttermilk drip off, then press each thigh firmly into the breading mixture. Fry in the hot oil for 5 to 7 minutes per side until deeply golden and cooked through, then transfer to a wire rack.
Make the Aioli:
In a small bowl, stir together mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper until smooth. Taste and adjust seasoning as needed.
Toast the Buns:
If you like, butter the cut sides of the brioche buns and toast them in a skillet until golden and fragrant. This step is optional but adds a lovely buttery crunch.
Assemble the Sandwiches:
Spread aioli generously on both sides of each bun, layer with lettuce if using, add a fried chicken thigh, pile on a generous mound of crispy onions, and close with the top bun. Serve immediately while everything is still warm and crispy.
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A juicy Crispy Onion Chicken Sandwich with golden fried onions and a soft brioche bun, perfect for a weeknight dinner.  Pin It
A juicy Crispy Onion Chicken Sandwich with golden fried onions and a soft brioche bun, perfect for a weeknight dinner. | sweetcairn.com

One evening, I packed these sandwiches for a picnic and watched my friends devour them in minutes, aioli smeared on their faces, laughing between bites. Someone said it tasted like summer, and I realized that's exactly what good food does: it captures a feeling and shares it. That night, under string lights and surrounded by people I love, this sandwich became more than dinner, it became a reason to gather.

Making It Your Own

If you like heat, stir a teaspoon of hot sauce into the aioli or add a pinch of cayenne to the breading for a spicy kick. I've also swapped chicken breasts for thighs when that's what I had on hand, just watch the cooking time since breasts can dry out faster. Some people love adding pickles or a tangy slaw on top for extra crunch and acidity, and honestly, both are fantastic choices. This recipe is forgiving and welcomes your tweaks, so don't be afraid to experiment.

Serving Suggestions

These sandwiches are rich and satisfying on their own, but a side of crispy fries or a simple green salad balances the plate nicely. I like to serve them with extra pickles and a cold drink, maybe lemonade or iced tea, especially on warm days. If you're feeding a crowd, set up a DIY sandwich bar with all the toppings and let everyone build their own. It turns dinner into an event, and cleanup is surprisingly easy since everyone's too busy eating to make a mess.

Storage and Reheating

Fried chicken is always best fresh, but leftovers can be stored in an airtight container in the fridge for up to two days. Reheat the chicken in a 375°F oven for about 10 minutes to bring back some of that crispiness instead of microwaving, which makes it soggy. The onions lose their crunch quickly, so I recommend frying them fresh each time, and the aioli keeps well in the fridge for up to a week.

  • Store chicken and onions separately from the buns to prevent sogginess.
  • Reheat in the oven, not the microwave, for the crispiest results.
  • Make extra aioli because it's delicious on just about everything.
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Freshly assembled Crispy Onion Chicken Sandwich, featuring golden fried chicken thighs and crispy onions on a buttery toasted bun. Pin It
Freshly assembled Crispy Onion Chicken Sandwich, featuring golden fried chicken thighs and crispy onions on a buttery toasted bun. | sweetcairn.com

This sandwich has earned a permanent spot in my kitchen rotation, and I hope it does the same for you. There's something special about food that makes people pause, smile, and ask for seconds.

Recipe FAQs

Can I use chicken breasts instead of thighs?

Yes, boneless, skinless chicken breasts work well as a substitute. Reduce the frying time to 4-6 minutes per side to prevent drying out, as breasts are leaner than thighs.

How long can I marinate the chicken?

Marinate for at least 30 minutes for basic flavor, or up to 4 hours for deeper seasoning. Avoid marinating longer than 8 hours, as the buttermilk can break down the chicken's texture excessively.

What oil temperature is best for frying?

Maintain 350°F (175°C) for both the chicken and onions. Use a thermometer for accuracy. Oil that's too cool results in greasy food, while too-hot oil burns the exterior before cooking through.

How do I keep the sandwich from getting soggy?

Toast the brioche buns lightly to create a moisture barrier. Spread the aioli on both bun surfaces, and add lettuce as a layer between the bun and hot chicken to prevent direct contact with the bun.

Can I make the aioli ahead of time?

Yes, prepare the aioli up to 24 hours in advance. Store it in an airtight container in the refrigerator. Give it a quick stir before use, as the ingredients may separate slightly.

What's the best way to reheat leftovers?

Reheat the fried chicken in a 375°F (190°C) oven for 10-12 minutes to restore crispness, rather than using a microwave which creates sogginess. Assemble the sandwich fresh with room-temperature aioli.

Crispy Onion Chicken Sandwich

Buttermilk-marinated fried chicken topped with crispy onions and garlic aioli, served on a toasted brioche bun.

Prep Duration
25 minutes
Time to Cook
25 minutes
Time Needed
50 minutes
Recipe by Hunter Phillips


Level Medium

Cuisine American

Makes 4 Portions

Dietary Notes None specified

Ingredient List

Chicken & Marinade

01 4 boneless, skinless chicken thighs
02 1 cup buttermilk
03 1 teaspoon garlic powder
04 1 teaspoon paprika
05 ½ teaspoon salt
06 ½ teaspoon black pepper

Breading

01 1 cup all-purpose flour
02 ½ cup cornstarch
03 1 teaspoon smoked paprika
04 1 teaspoon salt
05 ½ teaspoon ground black pepper

Crispy Onions

01 1 large yellow onion, thinly sliced
02 ½ cup all-purpose flour
03 ½ teaspoon salt
04 ½ teaspoon black pepper
05 Vegetable oil for frying

Aioli

01 ½ cup mayonnaise
02 1 large garlic clove, minced
03 1 tablespoon fresh lemon juice
04 ½ teaspoon Dijon mustard
05 Salt and pepper to taste

Assembly

01 4 brioche buns, sliced
02 Butter for toasting buns, optional
03 Lettuce leaves, optional

Steps

Step 01

Prepare Marinade: In a bowl, whisk together buttermilk, garlic powder, paprika, salt, and black pepper. Add chicken thighs and coat thoroughly. Cover and refrigerate for at least 30 minutes or up to 4 hours.

Step 02

Mix Breading Mixture: In a shallow dish, combine flour, cornstarch, smoked paprika, salt, and black pepper. Set aside.

Step 03

Coat Onions: In a separate bowl, toss sliced onions with flour, salt, and black pepper until evenly coated.

Step 04

Fry Onions: Heat 1 inch of vegetable oil in a large skillet to 350°F. Fry onions in batches for 2-3 minutes per batch until golden and crisp. Drain on paper towels.

Step 05

Bread Chicken: Remove chicken from marinade, allowing excess buttermilk to drip off. Dredge each thigh in the breading mixture, pressing firmly to adhere.

Step 06

Fry Chicken: Fry chicken in the same hot oil for 5-7 minutes per side until cooked through and golden brown. Transfer to a wire rack or paper towels to drain.

Step 07

Prepare Aioli: In a small bowl, combine mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper. Mix until smooth.

Step 08

Toast Buns: Optional: Butter and toast brioche buns in a skillet until golden brown.

Step 09

Assemble Sandwiches: Spread aioli on both sides of each bun. Layer with lettuce if desired, fried chicken, a generous mound of crispy onions, and top with bun half.

Equipment Needed

  • Mixing bowls
  • Large skillet or deep fryer
  • Tongs
  • Wire rack or paper towels
  • Knife and cutting board
  • Shallow dish for breading

Allergy Info

Look through each ingredient for allergens and check with a healthcare provider if you’re uncertain.
  • Contains eggs from mayonnaise
  • Contains wheat from flour and brioche buns
  • Contains milk from buttermilk and butter
  • Contains mustard from aioli
  • Buns may contain soy or other allergens—check labels if needed

Nutrition Info (each serving)

Figures are for reference only—always seek medical advice when needed.
  • Caloric Value: 670
  • Fats: 32 grams
  • Carbohydrates: 61 grams
  • Proteins: 32 grams