A family favorite, my boyfriend is also a fan and he's probably the pickiest eatter I know. Really easy to prepare aswell.

Sweet & Sour Meatballs:

1 lb Lean ground beef
1/8 cup Bread crumbs
1/8 tsp Pepper
1/8tsp Garlic ( Minced or Powder )
1/4 tsp (or less) Salt

Add a beaten egg if too dry to above ingredients, mix well before forming into balls then brown in a frying pan at low-medium heat.
Once meatballs are browned, set aside and in the same frying pan sautee chopped medium onion, chopped green pepper and chopped carrot in the leftover juices.

In a pot on the stove at med heat, careful not to burn add the ingredients below, whisking occasionally:

2/3 cup Water ( Or more depending on desired thickness )
2 tbsp Soya Sauce
2 tbsp Cornstarch
2 Chicken Boullion packets/cubes
1/3 cup Vinegar
2/3 cup Brown Sugar

Once thickened the sauce should appear almost translucent which means it's done, this may take awhile depending on how much you want to risk the cooking process by raising the heat.
Mix together in an oven safe dish and bake in a pre-heated oven at 350 degrees for 15-20 minutes.
Serve over top of white/brown rice, garnish with seasame seeds.