Preheat the oven to 400°F. Arrange 3 medium-large scrubbed and trimmed beets in a small baking dish and fill it with enough water to submerge the beets 1 inch. Season with salt, cover the dish with foil, and bake in the oven for 30-40 minutes, until the beets are fork tender. Allow beets to cool enough to handle. Remove skins with a paring knife—they should come off easily. Dice beets and set aside in a medium mixing bowl.