This is one of the best ways to enjoy newly harvested root vegetables and new-crop garlic. Cooking the beets and potatoes separately is a must although the method is the same.
To make the aioli: Separate the cloves from 1 head of garlic — 12 small cloves or 6 large ones — and then peel them.
Chop the garlic roughly, then add along with 1/2 t. salt to a mini-food processor (or use a mortar and pestle) and puree. Add 1 egg yolk, then very slowly drizzle in 2 C. of high quality olive oil as you run the processor so that it emulsifies. Add a little lemon juice to taste if you like.
Wash 1 lb. Potatoes carefully to avoid removing the skins. Scrub the 1 bunch worth of Beets. Remove the tough stems from the greens and wash them as well.
Heat water for a steamer and cook the potatoes first until just fork-tender — around ten minutes, or less for the very small ones. Remove from the steamer and drop into a bowl of cold water.
Add the beets to the steamer and cook until they are completely tender, 15-20 minutes. If you like, steam the greens as well after the roots are done and serve alongside.
Serve the vegetables whole or in quarters, drizzled with the aioli. Sliced cucumbers or carrots make for a crunchy accompaniment.