The easiest way to cook beets is to microwave them whole in a covered container with just a little water at the bottom. Start with 4 minutes, then test and add a minute more at a time until you can pierce through the beet or beets, with a little resistance. If you prefer not to microwave, simply cook the beet or beets whole in a saucepan with plenty of water to cover, simmering gently but steadily until you can pierce through with a bit of resistance, about 10 to 20 minutes depending on the size of the beets.
Allow the beets to cool, then peel and cut into ½-inch dice.
For the potatoes, once again, the easiest thing to do is to microwave them until just tender. Otherwise, you can cut the uncooked potatoes into ½-inch dice and simmer in enough water to cover in a medium saucepan until just tender. Drain and allow to cool.
Once cool, cut the potatoes into ½-inch dice.
Combine the cooked and cooled potatoes with the remaining ingredients in a serving container. Add the beets last and stir in gently so that they don’t bleed too much into the other ingredients.
Allow to stand for 20 to 30 minutes if time allows, or serve at once.