Why It Works
- The potato adds extra starch to the pasta water, helping to bind the sauce and absorb excess oil from the pesto.
- Tossing it all together off the heat preserves pesto's fresh flavor.
This classic Genovese method of preparing pasta with pesto includes cubes of potato and pieces of green bean, all cooked together in the pasta pot until tender.
- Kosher salt
- 1 pound (450g) dried pasta, such as trenette, linguine, or mafalde
- 5 ounces peeled Yukon Gold potato (140g; about 1/2 medium), cut into 3/4-inch cubes
- 4 ounces (110g) green beans or haricots verts (about 20 green beans or 30 haricots verts), stems trimmed and cut into 1-inch lengths on a bias
- 1 recipe pesto sauce
- Extra-virgin olive oil, for drizzling
- Grated Parmigiano Reggiano, for serving
In a large pot of salted boiling water, boil pasta, potato, and green beans until pasta is al dente and potato and green beans are very tender. Drain, reserving 1 cup cooking water, and transfer pasta, potato, and green beans to a large mixing or serving bowl.
Add pesto sauce to pasta along with 1/4 cup pasta cooking water. Toss well to emulsify pesto and pasta water into a creamy sauce. Add more pasta water, 1 tablespoon at a time, as needed, if pasta is too dry. Drizzle in fresh olive oil, if desired. Serve with Parmigiano Reggiano on the side.