Not guaranteed to be a completely unsloppy experience, but these filled kaiser rolls come close.
Heat olive oil in a large skillet over medium heat. Add onion, celery, carrot, green pepper, and garlic: saute until tender. Stir in tomatoes, chili powder, tomato paste, vinegar, and pepper. Cover, reduce heat, and simmer 10 minutes.
Stir in kidney beans, and cook an additional 5 minutes.
Cut a 1/4 inch slice off the top of each kaiser roll; set aside. Hollow out the center of each roll, leaving about 1/2 inch thick shells; reserve the inside of rolls for other uses.
Spoon bean mixture evenly into rolls and replace tops. Serve immediately.
Per Serving: 204 calories; protein 7.8g; carbohydrates 34.6g; fat 3.9g; sodium 488.8mg.