How long do you boil potatoes for mashed potatoes?

Instructions:

1. Place the potatoes in a large pot and add enough cold water to cover them by 1 inch.

2. Bring the water to a boil over medium-high heat, then reduce the heat to medium-low and simmer until the potatoes are tender when pierced with a fork, about 15-20 minutes.

3. Drain the potatoes and return them to the pot.

4. Mash the potatoes with a potato masher, adding butter, milk, sour cream, salt, and pepper to taste.