- Line the inside of a sieve with three layers of cheesecloth or two layers of paper towel. Place the sieve over a bowl.
- In another bowl, combine the yogurt with the horseradish and salt. Pour the mixture into the prepared sieve. Cover and let strain in the refrigerator for 5 hours (see note).
- With the rack in the middle position, preheat the oven to 425°F (220°C).
- Place the beets on a piece of foil. Seal tightly into a packet and place on a baking sheet. Bake for 40 minutes or until the beets are tender. Open the foil packet and let the beets cool. Peel the beets.
- Meanwhile, in a small skillet, bring the orange juice to a boil. Add the currants. Remove from the heat. Let cool.
- In a small food processor, purée one of the beets until as smooth as possible. Season with salt and pepper.
- Cut the second beet into small dice. Place in a bowl. Add the currant and orange juice mixture, as well as the strips of orange zest. Season with salt.
- Spread the yogurt over the crackers. Top with the beet purée and diced beet mixture. Sprinkle with the sumac and garnish with the mint leaves. Serve immediately.
The longer the yogurt is left to strain, the thicker it will be.