5 medium beets, peeled, cut into 5 centimeter chunks
3 medium carrots, peeled, cut into 5 centimeter chunks
1 medium red onion, peeled, cut into 8 wedges
4 cloves garlic, skin on
6 sprigs fresh thyme
2 tablespoons (30 milliliters) olive oil
1/2 teaspoon (3 grams) kosher salt, plus more
1/4 teaspoon (1 gram) freshly ground black pepper, plus more
4 cups (960 milliliters) chicken or vegetable broth
1 tablespoon (15 milliliters) balsamic vinegar
2 teaspoons (10 grams) prepared horseradish
1 teaspoon (10 grams) Dijon mustard
3 tablespoons (8 grams) chopped dill, plus more for serving
2 teaspoons (10 milliliters) lemon juice
Sour cream, for serving
Optional: 1 tablespoon (15 milliliters) vodka
Heat oven to 400°F (205°C).
Toss beets, carrots, onion, garlic and thyme on a large baking sheet with olive oil, 1/2 teaspoon (three grams) salt and 1/4 teaspoon (one gram) pepper. Spread into an even layer and roast for 30 minutes, stirring halfway. Once cool enough to handle, squeeze garlic from skins.
Transfer vegetables to a medium saucepan and add broth. Bring mixture to a boil and reduce heat to maintain a simmer. Cover and cook until vegetables are very tender, about 50 to 60 minutes.
Remove thyme from saucepan then transfer mixture into a blender. Purée until smooth (in batches, if necessary).
Return mixture to saucepan over medium-low heat. Stir in vodka (if using), vinegar, prepared horseradish, Dijon mustard, dill and lemon juice. Season with salt and pepper to taste. Cover and cook for ten minutes.
Serve hot or cold, topped with sour cream and dill.