Step 1

Preheat the oven to 375 degrees F (190 degrees C). Lightly spray a baking sheet with cooking spray.

Step 2

Mix ground beef, bread crumbs, bell pepper, onion flakes, eggs, garlic, soy sauce, salt, and pepper in a large bowl until well combined. Shape mixture into 1-inch meatballs; you should have approximately

Step 3

Bake meatballs in the preheated oven until no longer pink inside, 15 to 20 minutes. An instant-read thermometer inserted into the center should read at least 160 degrees F (71 degrees C). Remove from the oven and drain on paper towels to remove excess oil. Place in a large bowl or casserole dish.

Step 4

Combine broth, teriyaki sauce, and vinegar in a saucepan over medium heat; mix until boiling. Stir water and cornstarch together in a small bowl and stir into the saucepan; cook until thick, 1 to 2 minutes.

Step 5

Pour sauce over meatballs and gently toss until coated. Serve immediately or keep warm in a slow cooker or in a 275 degrees oven (135 degrees C) covered with foil.