It really doesn’t matter whether you use cannellini or borlotti beans here. I tend, more often, to use cannellini, just out of habit I think, but adore the soft pink specklediness of borlotti, too. I suppose it’s just that I associate them more with soups. No matter: choose which you prefer.
Soak the beans overnight in cold water. Drain them, and put them in a thick-bottomed large saucepan along with the onion, carrot and the 3 sage leaves. Cover by about 15cm with cold water, bring to the boil and simmer for 1–1½ hours or until done. How long it actually takes depends on the age of t