Genoese pesto pasta with potatoes and green beans (Trenette al pesto)

1. For the pesto, pick the basil leaves (don't wash them, just wipe them), then pound the garlic with the coarse salt and pine nuts in a mortar or blender to a paste; add the basil in batches and work until creamy.

2. Stir in the grated parmesan and pecorino, then drizzle in enough extra virgin olive oil to make a thick, glossy pesto.

3. Peel the potatoes and cut them into 1 cm cubes; trim the green beans and cut them into 3 cm pieces.

4. Boil the potatoes and beans in a large pot of salted water for 5 minutes, then add the pasta and cook everything together for the time given on the pasta packet.

5. Set aside a ladleful of cooking water, drain the pasta with the vegetables and toss thoroughly in a large bowl with the pesto and 2-3 tablespoons of cooking water.

6. Serve at once with a little grated parmesan - pesto is never heated, only warmed by the hot pasta.

Tip: The potato starch makes the pesto creamier - in Liguria this is the classic "complete" version; pesto keeps for 3 days in the fridge covered with oil.