Toast nuts in an even layer in a skillet over medium heat (or in a 350°F oven 5 to 10 minutes) to bring out a deep, rich flavor. Cool the nuts completely before making your pesto to prevent the sauce from getting gummy.
Pesto is a sauce, not a paste, so avoid overprocessing. Pulse the food processor just until everything is combined and evenly pureed. Stop there. Big flecks of basil, garlic, and nuts are good.
Do yourself a flavor favor and freshly grate your cheese by hand. We recommend stirring in the cheese after processing the other ingredients to keep the mixture from becoming pasty.
Change the consistency of pesto by adding more or less oil. Thicker pesto works well to spread onto sandwiches, while thinner pesto tosses better with veggies and pasta. For an extra kick of flavor, add a couple teaspoons lemon juice.