Marry all the ingredients without overwhelming them.
Pesto Genovese is made with seven sacred ingredients: basil, extra-virgin olive oil, Parmigiano-Reggiano, Pecorino Romano, Mediterranean pine nuts, garlic, and salt. We do our best here in Montana, which is why I substitute walnuts for pine nuts, but I am over the moon about locally grown basil becoming more readily available—thanks to Yellowstone Valley Farms and Root Cellar Foods.
A mortar and pestle are the traditional tools of preparation, as they create the best texture and flavor (not to mention a heavenly aroma in your kitchen), but you can make pesto in a food processor too.
MAKES ABOUT 1 CUP, ENOUGH TO SAUCE 1 POUND OF PASTA
1 garlic clove
Several pinches of flaky salt (½ teaspoon maximum)
¼ cup lightly toasted walnuts
2 cups basil leaves
½ cup Parmigiano-Reggiano, grated
½ cup extra-virgin olive oil
Using a mortar and pestle, crush the garlic with several pinches of salt. Add the walnuts and crush into a paste. Add the basil leaves gradually, using a circular motion to crush and tear the leaves against the wall of the mortar. After all the basil is incorporated, add the cheese and olive oil in a thin stream and stir with the mortar to incorporate. As you mix, remember these words from Nuova Marmotecnica, the makers of a fine selection of marble mortars and pestles: “[It is] ideal to marry all the ingredients without overwhelming them.” Buon appetito!