Like many things with only a few ingredients, how you do it is as important as what you add. Here’s how we do it:
Peel the potatoes and drop into a large pot of cold water. Cut large potatoes into chunks, but keep the pieces large. After all the potatoes are peeled, pour off the starchy water and add fresh cold water and about 1 tablespoon salt.
Place on the stove over high heat. Bring to a boil, then reduce the heat to medium to maintain a brisk simmer. When potatoes boil, the starch sets and can make them fall apart, so they become too watery. It’s better to cook them longer at a lower temperature. Cook for 30 to 40 minutes. To make sure they’re done, try this trick: Stick the tip of a sharp knife into a few chunks of potato. If you can slide in the knife but the potato still clings to the blade, they aren’t quite done.
Drain the potatoes and return to the empty pot on the still-hot burner. Shake the pot a few times to help remaining water evaporate. Then mash the potatoes roughly with a masher or squeeze through a ricer. Whisk in the remaining ingredients with a sturdy whisk or wooden spoon.Butter or milk first? The order makes a difference: