Pesto doesn’t have to be made from basil. Pesto is a generic Italian term for making something by pounding. The ancient Romans also ate a dish called moretum; a type of herb cheese spread eaten with bread. It was typically made with herbs, fresh cheese, salt, oil and some vinegar along with different kinds of nuts which were sometimes added. The contents were crushed together with a mortar and pestle. It is only natural that these two dishes, so closely related, would get the names moretum and pesto.
Tonight I made a pesto using walnuts and arugula. Although arugula is not a herb like basil, its color and unique peppery flavor make a great substitute. Here’s what I did:
2 small garlic cloves
3 ounces walnut pieces (about ¾ cup), toasted and cooled
4 ounces arugula, trimmed and roughly chopped
½ teaspoon coarse salt
1 ounce Parmesan cheese, finely grated (about 1/3 cup)
1 pound spinach linguine
3 tablespoons extra-virgin olive oil plus extra if needed
Freshly ground pepper
Pulse garlic until very finely chopped. Add walnut pieces, arugula, Parmesan and process until a coarse paste forms. Drizzle olive oil into mixture while processing. Additional olive oil can be added if the mixture is too clumpy. It is always better to use less olive oil as it is easy to add but very difficult to remove. Transfer to a serving bowl. Stir in the salt and set aside. Even more olive oil can be added if you feel the mixture is too dry. This can be made up to an hour ahead of time. Do not chill; keep at room temperature.
Bring a large pot of water to a boil. Add angel hair and cook until al dente according to package instructions, about 6 to 8 minutes. Drain in a colander, and immediately add to bowl with walnut-arugula mixture. Drizzle with the oil, and season with pepper. Toss thoroughly until coated evenly. Serve immediately.