4 (5- to 6-ounce) boneless, skinless chicken breasts , tenderloins removed (see illustration below) and breasts trimmed of any white or yellow fat
1/2 cup unbleached all-purpose flour
Salt and ground black pepper
2 tablespoons vegetable oil
2 tablespoons unsalted butter
1 medium onion , minced
1 1/2 cups long-grain white rice
3 medium cloves garlic cloves , minced or pressed through a garlic press (about 1 tablespoon)
Pinch red pepper flakes
4 1/2 cups low-sodium chicken broth
1 cup frozen peas
5 scallions , sliced thin
2 tablespoons fresh lemon juice
1. Following the illustration below, pound each chicken breast between two sheets of plastic wrap to a uniform 1/2-inch thickness. Place the flour in a shallow dish. Pat the chicken breasts dry with paper towels and season with salt and pepper. Working with 1 chicken breast at a time, dredge in the flour, shaking off the excess.
2. Heat the oil in a 12-inch nonstick skillet over medium-high heat until just smoking. Carefully lay the chicken breasts in the skillet and cook until lightly browned on both sides, 6 to 8 minutes. Transfer the chicken to a plate and pour off any fat left in the pan.
3. Add the butter to the skillet and melt over medium heat. Add the onion and 1/2 teaspoon salt and cook until the onion is softened, about 5 minutes. Stir in the rice, garlic, and red pepper flakes and cook until fragrant, about 30 seconds.
4. Stir in the broth, scraping up any browned bits. Nestle the chicken into the rice and bring to a simmer. Cover, reduce the heat to medium-low, and cook until the thickest part of the chicken registers 160 to 165 degrees on an instant-read thermometer, about 10 minutes.
5. Transfer the chicken to a clean plate, brushing any rice that sticks to the chicken back into the skillet, and tent the chicken loosely with foil to keep warm. Cover and continue to cook the rice over medium-low heat, stirring occasionally, until the liquid has been absorbed and the rice is tender, about 10 minutes.
6. Off the heat, sprinkle the peas over the rice, cover, and let warm through, about 2 minutes. Add the scallions and lemon juice and gently fold into the rice. Season the rice with salt and pepper to taste and serve with the chicken.