You need:
Spaghetti (or other pasta)
Tomatoes (dark red and ripe)
Olive oil
Balsamic vinegar

For variation, you can add also one or all of the following:
1 small onion or spring onion
4 or 5 dried tomatoes
1 small cucumber
1 bell pepper

This cold sauce is quickly made, very fresh, healthy, and has only a few calories.

Cut the tomatoes and the onion in pieces and put in a blender. Add the olive oil (less = less calories, more = smoother taste… you decide what’s more important), the balsamic vinegar, a dash of sugar, salt, pepper, capers, and dried tomatoes ( all except for cucumber and bell pepper), and blend to a fine sauce.
If you want, you can cut a cucumber and/or a bell pepper in very small pieces and add it to the blend.