Preparation Peel and quarter potatoes. Put potatoes and 1 tablespoon salt in a 3-quart pot and cover with cold water by 1 inch. Bring to a boil, covered with lid, then reduce heat and simmer, partially covered, until potatoes are very tender, 20 to 25 minutes. Reserve 1 cup cooking water, then drain potatoes in a colander and return to pot. Add oil, pepper, chives (if using), remaining 1/2 teaspoon salt, and 1/2 cup cooking water and mash with a potato masher or fork. Add more cooking water for a looser consistency.
Preparation Peel and quarter potatoes. Put potatoes and 1 tablespoon salt in a 3-quart pot and cover with cold water by 1 inch. Bring to a boil, covered with lid, then reduce heat and simmer, partially covered, until potatoes are very tender, 20 to 25 minutes. Reserve 1 cup cooking water, then drain potatoes in a colander and return to pot. Add oil, pepper, chives (if using), remaining 1/2 teaspoon salt, and 1/2 cup cooking water and mash with a potato masher or fork. Add more cooking water for a looser consistency.