- 1 1/2 pounds boneless, skinless chicken breasts, halved horizontally and thinly sliced
- Coarse salt and ground pepper
- 2 tablespoons olive oil
- 1 large onion, halved and thinly sliced
- 1 large red bell pepper, ribs and seeds removed, thinly sliced
- 3 cloves garlic, minced
- 1 1/2 teaspoons grated peeled fresh ginger
- 1/4 to 1/2 teaspoon red-pepper flakes
- 3 tablespoons soy sauce
- 3 tablespoons rice vinegar
- 1 1/2 teaspoons cornstarch, mixed with 1 tablespoon water
- 12 to 16 Boston lettuce leaves (about 2 heads)
- Season chicken with salt and pepper. In a large nonstick skillet, heat 1 tablespoon oil over high heat. Add half the chicken; cook, stirring constantly, until opaque throughout, 2 to 4 minutes. Transfer to a plate. Repeat with remaining chicken.
- Add remaining tablespoon oil to pan, along with the onion and bell pepper. Cook, stirring constantly, until onion is tender and golden, about 4 minutes (reduce heat if browning too quickly).
- Reduce heat to medium; add garlic, ginger, and red-pepper flakes; cook, stirring, until fragrant, 30 to 60 seconds.
- Stir in soy sauce, vinegar, and cornstarch mixture; remove from heat. Add chicken and any accumulated juices; toss to coat. Serve in lettuce cups or on top of rice.