2 tsp canola oil
2 red bell peppers,stemmed, seeded, and sliced thin
1 red onion, halved and sliced thin
salt and pepper
4 (6 ounce) boneless, skinless chicken breasts, trimmed, pounded if necessary
1/2 cup orange juice
3/4 cup minced fresh cilantro
1 TB Worcestershire sauce
4 garlic cloves, minced
2 tsp minced canned chipotle chile in adobo sauce
1 tsp yellow mustard
1 tomato, cored, seeded, and chopped, medium
3 scallions, sliced thin
8 whole-wheat flour tortillas, warmed
1. Heat the oil in a 12 inch skillet over medium high heat until just smoking. Add the bell peppers and onion and cook, stirring occasionally, until softened and well-browned, 5 to 7 minutes. Transfer to a bowl, season with salt and pepper to taste, and cover to keep warm.
2. Pat the chicken dry with paper towels and season with salt and pepper. Combine the orange juice, 1/2 cup of the cilantro, Worcestershire, garlic, and chipotles in the skillet. Add the chicken and bring to a simmer over medium-low heat, about 5 minutes. When the liquid is simmering, flip the chicken over, cover and continue to cook until the chicken registers 160 to 165 degrees on an instant-read thermometer, 10 to 12 minutes longer.
3. Transfer the chicken to a plate and shred it into bite-sized pieces when cool enough to handle. Meanwhile, continue to simmer the sauce over medium heat until slightly thickened and reduced to 1/4 cup, about 5 minutes.
4. Off the heat, stir in the mustard, tomato, scallions, remaining 1/4 cup cilantro, and shredded chicken. Season with salt and pepper to taste and serve with the pepper-onion mixture and warm tortillas.
From America's Test Kitchen Healthy Family Cookbook