How to Make It
Heat oven to 450° F. Wrap the beets in a large piece of aluminum foil and bake until easily pierced with a paring knife, 35 to 45 minutes. Let cool, then, using a paper towel, remove the skins. Thinly slice.
Heat the oil in a large skillet over medium-high heat. Add as much spinach as will fit in the skillet. Season with ¾ teaspoon salt and ¼ teaspoon pepper. Cook, tossing frequently and adding more spinach when there is room, until just wilted, 2 to 3 minutes. Stir in the vinegar.
Meanwhile, combine the goat cheese, raisins, and ¼ teaspoon pepper in a small bowl.
Divide the sliced beets, spinach, and goat cheese spread among the rolls.