fresh basil, walnuts or pine nuts, fresh grated parmesan cheese, a little salt and pepper, and a little olive oil
Put it all in the chopper attachment cup for an immersion blender (or a small food processor, or even a blender if you're making a larger amount) and chop, process, or blend away. Be careful how much salt and oil you add. I suggest adding a little at first and tasting to see if you need more.
Voila! Delicious pesto you can use right away or save for later.
My friend Emily suggests freezing pesto in ice cube trays. Then you can thaw it later to have just the right amount to toss with pasta. I made some last week and tossed it with Rising Moon Organics Artichoke & Olive Ravioli. Dinner was done in less than 20 minutes and the longest part of that was waiting for the water to boil.