You can also do this on the grill.
Slice 1 lb. of Roma tomatoes lengthwise.

Mince 4 cloves of garlic.

Remove leaves from 1 bunch of basil to make 1 C., then chop roughly.

Pour 2 T. olive oil onto a cookie sheet or large pyrex baking dish.  Arrange the garlic and basil more or less evenly around the pan, then sprinkle with salt and pepper.  Add a pinch of other fresh or dried herbs if you like.

Place the tomatoes face down on the pan.  Roast for 30-40 minutes.  Remove from the oven and allow to cool

Remove the tomato skins, then pour the sauce into a bowl.  Use a spatula to get all the good bits.  Mash a bit with a fork, or if necessary puree for a minute in the food processor.