- 01Roast the beets: Put them in a baking dish in one layer (if some beets are larger, halve them so they will cook evenly). Add about 2 inches water to the pan and cover tightly with foil. Bake at 375 degrees for at least an hour, or up to one and a half hours, until fork tender. Remove the foil, pour off the liquid and let cool for a few minutes, then peel while still slightly warm. Cut into wedges and set aside.
- 02Cut beet greens into 1-inch ribbons, then wash well 3 times in abundant cold water to remove any sand or grit. Bring a large pot salted water to boil. Add the greens and cook briefly till wilted, about 2 minutes. Drain, cool under running water, then squeeze out excess water.
- 03In a dry pan over medium heat, toast the coriander and cumin seeds until fragrant and just lightly browned, about 2 minutes. Grind to a coarse powder in a mortar or spice mill.
- 04Make the vinaigrette: Put the onion, garlic and vinegar in a small bowl and leave for 5 minutes or so, then whisk in the remaining ingredients.
- 05Make the yogurt sauce: Put the yogurt in small bowl. Add the garlic, salt and pepper, cayenne, cumin-coriander mixture, mint and olive oil.
- 06Season the beet wedges lightly with salt and dress with half the vinaigrette. In a separate bowl, lightly salt the greens and dress with remaining vinaigrette. Arrange dressed beets and greens on a platter and top with a little smear of the yogurt sauce. Sprinkle with dill, and pass the rest of the yogurt sauce at the table.