Step 1

Prepare the Beet Puree: Preheat oven to 350°F. Lay a 12-x10-inch piece of aluminum foil on a work surface. Place beets in center of foil. Rub with 2 tablespoons of the oil, and wrap foil tightly around beets. Place packet on a baking sheet, and roast in preheated oven until very tender when pierced with a knife, 1 hour 15 minutes to 1 hour 30 minutes. Unwrap and cool 15 minutes. Rub skins from beets; discard skins. Coarsely chop. Process chopped beets, vinegar, mustard, salt, and remaining 2 tablespoons oil in a food processor until smooth, about 1 minute, scraping down sides as necessary.

Step 2

Prepare the Yogurt Sauce: Stir together yogurt, dill, lemon juice, salt, and pepper in a small bowl.

Step 3

To assemble: Spread 1 tablespoon of the Beet Puree on bottom bread slices. Top with 3 slices beef and another tablespoon of the Beet Puree. Top with some of the cabbage. Spread 1 1/2 tablespoons of the Yogurt Sauce on remaining bread slices, and place on top of sandwiches.