Put the chopped onion in a saucepan with the extra virgin olive oil and heat it on a slow fire. Cook for 1 minute, until the onion becomes transucent.

Add the chopped potatoes and sauté them for a couple of minutes.

Add the tomato purée and 2 tbsp of water, mix and cook, covered until the potatoes are soft. Stir frequently while cooking and add water little by little as required.

When the potatoes are soft, season with salt and pepper, add the chopped parsley and keep aside.

Cook the linguine following the steps on How to cook pasta “al dente” in the Techniques page of this site.

Add 4 tablespoons of the water in which you are cooking the pasta, into the pot with the potato sauce if the liquid has dried up (potatoes absorb a lot of liquid and you need to keep the sauce moist!).

Drain the linguine and serve immediately with the potato sauce and grated Pecorino Romano on the top.