Step 1

Arrange a rack in the middle of the oven and heat to 425°F.

Step 2

Place the olive oil, vinegar, garlic, mustard, salt, and pepper in a mini chopper or food processor. Process continuously until thick and creamy, about 30 seconds. Transfer to a large bowl. Add the chicken thighs and mix well to coat.

Step 3

Transfer the chicken to a rimmed baking sheet and arrange in a single layer. Roast until the chicken is lightly browned and registers an internal temperature of 165°F, 20 to 25 minutes.