Servings: Makes 1 cup
Ingredients 1 small clove garlic , peeled1/2 teaspoon kosher salt1/2 cup walnuts2 cups packed fresh arugula leaves1/2 cup packed fresh basil leaves1/3 cup extra-virgin olive oil , plus more for storing2 tablespoons grated Parmesan cheese1 tablespoon fresh lemon juice
Place garlic and salt in a mortar. Add about 1/3 of the walnuts, arugula, basil, and olive oil. Using a pestle, crush ingredients against bottom and sides of mortar until a coarse paste forms.
Working in batches, add another 1/3 of the walnuts, arugula, basil, and olive oil, crushing as directed. Repeat with remaining batch. Stir in Parmesan and lemon juice; transfer to an airtight container, cover with a layer of extra-virgin olive oil, and refrigerate up to 3 days.
Note: This pesto can be made in a food processor: Simply combine the ingredients and blend 20 to 30 seconds, to a coarse paste. Chef Michela Larson prefers crushing them in a mortar with a pestle—a slower process, which she finds results in a more aromatic, flavorful pesto.