Crispy Onion Chicken Sandwich (Printer-Friendly)

Buttermilk-marinated fried chicken, crunchy onions, and garlic aioli stacked on brioche. Crispy, juicy, and satisfying.

# What You’ll Need:

→ 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

07 - 1 cup all-purpose flour
08 - ½ cup cornstarch
09 - 1 teaspoon smoked paprika
10 - 1 teaspoon salt
11 - ½ teaspoon ground black pepper

→ Crispy Onions

12 - 1 large yellow onion, thinly sliced
13 - ½ cup all-purpose flour
14 - ½ teaspoon salt
15 - ½ teaspoon black pepper
16 - Vegetable oil for frying

→ Aioli

17 - ½ cup mayonnaise
18 - 1 large garlic clove, minced
19 - 1 tablespoon fresh lemon juice
20 - ½ teaspoon Dijon mustard
21 - Salt and pepper to taste

→ Assembly

22 - 4 brioche buns, sliced
23 - Butter for toasting buns, optional
24 - Lettuce leaves, optional

# How-To Steps:

01 - Whisk together buttermilk, garlic powder, paprika, salt, and black pepper in a bowl. Add chicken thighs, ensuring complete coverage. Cover and refrigerate for at least 30 minutes or up to 4 hours.
02 - Combine flour, cornstarch, smoked paprika, salt, and black pepper in a shallow dish and set aside.
03 - Toss sliced onions with flour, salt, and black pepper in a separate bowl until evenly coated.
04 - 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.
05 - Remove chicken from marinade, allowing excess buttermilk to drip off. Dredge each thigh in the breading mixture, pressing firmly to ensure coating adheres properly.
06 - Fry chicken in the same hot oil for 5-7 minutes per side until golden brown and cooked through. Transfer to a wire rack or paper towels to drain excess oil.
07 - Combine mayonnaise, minced garlic, lemon juice, Dijon mustard, salt, and pepper in a small bowl and mix until smooth.
08 - Butter and toast brioche buns in a skillet over medium heat until golden, approximately 1-2 minutes per side. This step is optional but recommended for texture.
09 - Spread aioli on both sides of each brioche bun. Layer with lettuce if using, fried chicken thigh, and a generous mound of crispy onions. Top with bun half and serve immediately.

# Expert Advice:

01 -
  • The buttermilk marinade keeps the chicken ridiculously juicy even after frying
  • Cornstarch in the breading creates an extra shatter that stays crisp longer than you'd expect
  • Those fried onions add a sweetness and crunch that makes every bite different
  • The garlic aioli is so good you'll want to put it on everything for a week
02 -
  • Don't skip the resting time after frying, the chicken needs a minute on the rack to let the crust set and the juices redistribute
  • If your oil temperature drops too much between batches, the breading will absorb oil and turn greasy instead of crisp
  • Press the chicken firmly into the breading mixture, a thin coating won't give you that satisfying crunch
  • Slice the onions as thin as you can manage, thick slices won't crisp up the same way and can taste raw in the center
03 -
  • Use a thermometer to monitor your oil, consistent temperature is the difference between greasy and perfect
  • Let the chicken come to room temperature for ten minutes before frying so the inside cooks evenly
  • Press the breading into any bare spots before frying, those gaps will turn into sad uncoated areas
  • Don't crowd the pan when frying, it drops the oil temperature and makes everything soggy
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