Mix beef, milk, seasoning, onion powder, 1/2 teaspoon of the salt, 1/4 teaspoon of the pepper, and garlic powder in bowl. Using tablespoon, shape 1-1/4-inch meatballs, about 20.
In 2 batches, brown meatballs in oil in large deep skillet for 4 minutes. Remove to paper-towel-lined plate.
Add eggplant, zucchini, red pepper, onions, remaining 1/2 teaspoon salt and 1/4 teaspoon black pepper to skillet; cook 3 minutes.
Add meatballs and tomatoes to skillet. Cover; simmer 18 minutes or until vegetables are tender. Serve with noodles, if desired.