Pesto is just a lot of basil, ground up in a food processor with olive oil, parmesan cheese, fresh garlic, & lemon juice.  Some folks add some other green herbs or green veggies to it.  Some folks add pignoli nuts too.  It's a little tough to make in a blender because the blades are too high. Here is Toni's recipe:

PESTO SAUCE

1/2 LB FRESH BASIL

OLIVE OIL

6 GARLIC CLOVES

LEMON JUICE

PARMESAN OR ROMANO CHEESE

BLACK PEPPER

In a food processor or blender add a cup basil leaves, 4-5 tbsp olive oil, garlic, 2-3 tbsp lemon juice and 1 tbsp cheese. Blend till creamy. Keep adding liquids if mixture is dry. Repeat the steps till all of the ingredients are blended.

In a large pan bring water to boil for pasta. When done drain pasta, toss with sauce and serve.

Use cheese tortellini with this or, shells, bowties, ziti or linguini are ideal.

Ingredients that can be pesto: fresh parsley, sundried tomatoes, olives, anchovies, artichoke hearts, and capers. Cheese is optional for the non-herb pestos.