Cut roast in half; brush with browning sauce if desired. Combine the flour, salt and pepper; rub over meat. Place onion in a 3-qt. slow cooker; top with roast.
Drain pineapple, reserving juice; refrigerate the pineapple slices. In a small bowl, combine the brown sugar, cornstarch and ginger; whisk in the broth, soy sauce, garlic and reserved pineapple juice until smooth. Pour over meat. Cook, covered, on low for 6-8 hours.
Add pineapple and green pepper. Cook 1 hour longer or until meat is tender.