Total Time: 20 minutes
Yield: 24 (⅓-cup) servings
To make the pesto, pulse garlic, pine nuts or walnuts, and watercress or arugula in a food processor until coarsely chopped. Add olive oil and lemon juice, and pulse to combine. Scrape down the sides of the bowl and taste. Adjust seasoning with sea salt, black pepper, and additional lemon juice, and pulse to blend.
Cook the pasta per package instructions. Drain pasta, reserving ½ cup of the cooking water. In a large bowl, add cooked pasta, 3 tablespoons of the pesto, and a small amount of the cooking water. Toss to coat. Add additional pesto and cooking water to taste. Adjust seasoning to taste. Serve immediately garnished with diced tomato and Parmesan cheese, if desired.
Watercress, a close cousin to arugula, contains a high concentration of vitamin C and may have cancer-fighting properties. You can find this aquatic, leafy vegetable in the produce section of most markets.
Extra pesto can be used for sandwich spread, raw vegetable dip, or pizza sauce. Pesto can be stored in an airtight container in the refrigerator for 3 days. Also, you can freeze pesto in ice cube trays and store in freezer bags for up to 6 months.