When are potatoes done?

"Hi on behalf of Expert Village my name is Andrea Spano and I'm going to show you a couple of soups today from my new book Not Just Desserts. I think it is time to test the potatoes now remember we are boiling the potatoes approximately 34-40 minutes about 3 pounds of potatoes and about 1/2 onion quartered, margarine, the jalapeños potato peppers and lets see how they are doing now. Okay. I can see that the potatoes are very soft you see how the fork runs easily into the potato. So it is at this point I'm going to shut the soup off and let it cool down a little bit before we puree it. This soup is a great autumn soup, it's very it is nice and rich but it is simply delicious."