- 6 medium beets (2 1/4 lb with greens), trimmed, leaving 1 inch of stems attached
- 1 1/4 cups cider vinegar
- 6 tablespoons water
- 1/2 cup sugar
- 1 tablespoon mustard seeds
- 1 teaspoon whole allspice
- 1 teaspoon cumin seeds
- 2 small red onions, cut into 1/2-inch-thick wedges
- 1 pint grape or cherry tomatoes, halved
- Preheat oven to 425°F.
- Wrap beets tightly in foil to make 2 packages and roast in middle of oven until tender, about 1 1/4hours.
- While beets roast, simmer vinegar, water, sugar, and spices, stirring occasionally, 15 minutes. Add onions and simmer, stirring, 2 minutes. Pour pickled onions with liquid and spices into a bowl and cool, stirring occasionally, to room temperature.
- Unwrap beets and, when just cool enough to handle, slip off skins and remove stems. Cut beets into 1/2-inch-thick wedges and transfer to a serving bowl with tomatoes. Drain pickled onions in a sieve set over another bowl and discard allspice. Add onions (with remaining spices) and 2 tablespoons pickling liquid to beets and toss well. Season with salt and pepper.