Cut potatoes for salad into two-inch chunks and place them in a bowl of cold lemon water; otherwise boil them intact. Place the potatoes in a pot. Cover the potatoes with cold water by 2 inches and add a pinch of salt. Bring the water to a boil. Lower the heat to a simmer when the water starts to boil. Simmer the potatoes uncovered until they pierce easily with a paring knife or skewer — 10 to 20 minutes for whole potatoes and 5 to 10 minutes for diced potatoes. Remove finished whole potatoes with a slotted spoon.