A decent tomato sauce is not at all difficult, and very useful. You can use it as the base for other dishes- pizza sauce, the lubrication for meatballs and pasta. It's cheap to make and is pretty non-threatening to children who are fussy eaters (though the basil might be a bit too green).
1 tbsp olive oil
1 medium onion, peeled and chopped
2 cloves of garlic, peeled and finely chopped
800g tinned tomatoes
Good lump of unsalted butter
pinch sugar (if needed)
Basil leaves, a good handful.
In a heavy bottomed saucepan, fry the onion until softened in the olive oil. Add the garlic and cook for about 1 minute. Once the garlic has release its scent, add the tin of tomatoes. Turn up the heat to medium high, and let it bubble away until thick and pulpy.Stir from time to time, otherwise the bottom will burn. Season with salt and pepper, and some sugar if you think it needs it (I often do). You can add the pepper before this stage, but not the sugar or salt- after reducing it down the flavour will taste too concentrated, so wait until you reach the consistency you like. Stir in a big lump of butter, letting it melt in the residual heat. Just before serving, stir in the basil leaves, torn up roughly with your hands.