If you want something a bit posher, but quick for one. (Multiply up for more):
A large tomato
Two spring onions
Clove of garlic
Good Squeeze of tomato puree
Salt
Pepper
Teaspoon of best olive oil
2 to 3 leaves of basil
Half glass of red wine or water
Chop tomato, spring onions and garlic. Tear up basil leaves. Mix all these in a cup with the tomato puree, olive oil and white wine. Season. Microwave for two minutes.
Put the meatballs in the sauce and cook until done, either in the microwave or a small pan.