Step 1

Heat 2 tablespoons of the oil in a large skillet or braiser over medium-high heat. Season the chicken all over with the salt.

Step 2

Once the oil is glistening, add the chicken to the skillet. Cook until browned, 3-4 minutes per side. Continue cooking, turning occasionally, until the internal temperature of the chicken reaches 165°F on an instant-read thermometer, 5-6 minutes more. Transfer the chicken to a plate.

Step 3

Reduce the heat to medium and add the remaining 1 tablespoon of olive oil to the skillet. Add the shallot and cook, stirring, until lightly browned, 2-3 minutes. Stir in the garlic and rosemary and cook until fragrant, about 1 minute more. Stir in the chicken stock and mustard and bring to a simmer over high heat. Once simmering, reduce the heat to medium-low and cook until reduced by half, 2-3 minutes.

Step 4

Stir in the lemon zest, lemon juice, pepper, and butter until the butter melts. Taste and season with salt and more lemon juice if desired. Return the chicken to the skillet and turn to coat.

Step 5

Serve the chicken and sauce over rice or couscous.