Sauce for 1 lb. Pasta
Traditionally prepared in a mortar, this is easy in a food processor or blender. Puree the leaves with the nuts, garlic, and salt until smooth. Add the cheese, and then gradually add the oil to make a thick, creamy sauce.
You can substitute another ½ c. of cheese for the pine nuts, if they are unavailable. Versions substituting walnuts or using dried basil should be avoided at all costs!
This can be refrigerated in a jar, covered with a thin skin of olive oil for several weeks. It can only be made in the late summer when fresh basil is available in quantity; however, it can be successfully frozen for future use by freezing the sauce, minus the cheese, in an ice cube tray, and storing in a heavy zip lock bag for up to a year. Thaw and add grated cheese, and you're ready to go.
This sauce is also very good added to soups (such as minestrone) or in an omelet.
It can be combined with butter (1 part pesto to 2 parts butter) and used on vegetables, mashed potatoes...
It can be stirred into bottled mayonnaise which makes a great potato salad.
1 part pesto, 1 part wine or rice vinegar, and 2 parts olive oil makes a great salad dressing.