4 5-oz boneless, skinless chicken breasts, each cut in half crosswise to make 2 thin slices
1/2 tsp chile powder
Pinch fresh ground black pepper
4 1/2-inch-thick slices fresh pineapple ([b]TIP[/b]: Try cutting pieces into 11 2 x 3-inch rectangles to fit perfectly over chicken.)
1 tsp safflower oil, divided
4 2-oz whole-grain rolls, split and toasted
2 small tomatoes, each cut into 4 slices
In a small bowl, mash avocado with cilantro,lime juice and 1/8 tsp salt; set aside.
Sprinkle chicken evenly with chile powder, 1/4 tsp salt and pepper. Sprinkle pineapple slices with remaining 1/8 tsp salt.
Heat a large grill pan on medium-high and brush with oil. Working in batches if necessary, grill chicken for 6 to 8 minutes, turning halfway, until no pink remains in center. Transfer chicken to a plate to rest for 4 to 5 minutes. Just when chicken comes off heat, add pineapple to grill pan and cook until grill marks appear, 2 to 3 minutes per side.
Divide avocado over bottom halves of rolls. Top each with 2 pieces chicken, 1 pineapple slice and 2 tomato slices. Sandwich with tops of buns.