- 2 skinless boneless chicken breast halves (1 lb total), halved horizontally
- 5 tablespoons extra-virgin olive oil
- 1 teaspoon dried oregano
- 1 teaspoon salt
- 1/4 teaspoon black pepper
- 3 tablespoons red-wine vinegar
- 1 garlic clove, minced
- 2 (10-inch) sub rolls, halved horizontally and center hollowed out
- 1 lb red bell peppers, tender-roasted (procedure precedes) and cut lengthwise into 1-inch strips
- 2 cups watercress (tough stems discarded)
- Special equipment: a well-seasoned cast-iron ridged grill pan
- Rub chicken with 1 tablespoon oil, oregano, 1/4 teaspoon salt, and 1/8 teaspoon pepper and marinate at room temperature 30 minutes.
- Whisk together vinegar, garlic, 3/4 teaspoon salt, and 1/8 teaspoon pepper and add 1/4 cup oil in a slow stream, whisking until emulsified. Drizzle cut sides of bread with half of dressing and toss roasted peppers with remainder.
- Heat grill pan over moderately high heat until hot, then grill chicken, turning over once, until just cooked through, 4 to 6 minutes total. Make sandwiches with chicken, peppers, and watercress.