I use a mortar and pestle for my pesto. I feel the flavors are brighter and the pesto holds its color and flavor longer. The pestle releases all the basil juices into the mortar so there is more basil aroma. Food processors heat the pesto and “cook” the basil, which helps the discoloration. Food processor blades dull quickly and rather than making a clean cut to the basil they tear it, speeding oxidization. I give the food processor version of this recipe further down. If using the food processor, I recommend doing a double batch as a single recipe is hard to get right in a standard sized processor bowl. Also, I just like the process of using the mortar and pestle as I find it meditative. I am more engaged with the food, the sound of the nuts grinding, and especially the smell as the basil gives up its juices. I like pesto for a lot more than just pasta. I mix it into farro or other whole grains, or toss vegetables with it. I also love it as a smear on sandwiches.