Scrub the potatoes under cold water and cut into bite sizes pieces. Boil for a few minutes, until half-cooked. Remove and rinse with cold water. Repeat for the beans, which should cook only for a couple of minutes.
In a large skillet over medium heat, sauté the onion in olive oil until golden. Add the potatoes and cover for about 5 minutes. Add the white wine. After a few minutes, add the beans and cook for a few more minutes. Add salt and pepper.
Bring a large pot of salted water to a boil. Cook the pasta until al dente and drain, reserving some of the cooking water. Cook together for a minute or 2, and add some reserved water if it seems dry. Mix in the Grana Padano.
Serve immediately, with a sprinkle of black pepper and Grana Padano as desired.