Place pineapple, chile sauce, soy sauce, and crushed red pepper in a crock pot. Mix well.
Season beef with 1/8 teaspoon salt and 1/8 teaspoon pepper and add to the crock pot. Add onion and stir to coat.
Cover and cook on high for 3 to 4 hours or on low for 7 to 8 hours.
Season with additional crushed red pepper, if desired and serve with tomatoes, if using. Serve with excess sauce and toothpicks. Yum!
Cook's Note: Alternatively, recipe can be baked in the oven, covered, at 325 degrees F for 3 to 4 hours.
PER SERVING (1/5th of recipe, about 6 "bites" with sauce): 196 calories, 4.5g fat, 313mg sodium, 18g carbs, 0.5g fiber, 15g sugars, 19.5g protein