1. Preheat broiler to high.
2. Place first 3 ingredients on a jelly-roll pan; broil 9 minutes, turning after 5 minutes. Combine tomatillo mixture, cilantro, stock, and flour in a blender; process until smooth.
3. Sprinkle chicken with salt and pepper. Heat a large skillet over medium-high heat. Add oil to pan; swirl to coat. Add chicken to pan, meaty side down; cook 5 minutes or until browned. Turn chicken over; top with tomatillo mixture. Partially cover pan; reduce heat to medium-low, and simmer 9 minutes or until chicken is done. Sprinkle with tomatoes; top with crema.