Preheat oven to 350 degrees F. Sprinkle chicken lightly with salt and black pepper. In a large skillet, heat oil over medium-high heat. Add chicken; cook about 4 minutes or until brown, turning once. (If necessary, brown chicken in batches.) Transfer chicken to an ungreased 3-quart rectangular baking dish. Drain pineapple, reserving 2/3 cup juice. Spoon pineapple chunks evenly over chicken; set aside.
For sauce, in a medium saucepan, whisk together the reserved 2/3 cup pineapple juice, cranberry sauce, cornstarch, brown sugar, vinegar, orange juice concentrate, sherry, soy sauce, and ginger. Cook and stir over medium heat until thickened and bubbly. Pour over chicken and pineapple in dish.
Bake, covered, for 25 minutes. Add sweet peppers, stirring gently to coat with sauce. Bake, uncovered, about 5 minutes more or until chicken is no longer pink (170 degrees F). Makes 8 servings.