Bring a large pan of salted water to the boil for the pasta.
Heat oil in a frying pan or wok.
Add the sliced potatoes and cook for a few minutes until golden. Stir in the beans, cream water and pesto. Gently bring the sauce to the boil. Season, then reduce the heat and simmer for 2 minutes.
Cook the linguine according to the packet instructions until al dente, then drain.
Pour the linguine into the sauce and cook for a couple of minutes.