Grab beets, orange zest, and a few other ingredients to make this quick and colorful holiday side.
Using a grater or a food processor fitted with the shredding disk, grate the beets. In a large bowl, toss the beets with the zest, cumin, 1 tsp. salt, and 1/4 tsp. pepper. Add the flour, a few spoonfuls at a time, tossing to combine.
Heat a medium (12-inch) nonstick skillet over medium. When the pan is very hot (after about 2 minutes), add the butter and cook until the butter is dark golden, about 3 minutes. Add the beets. Using a spatula, press the beets into an even layer that fills the pan. Cook until the bottom is crisp, about 10 minutes. Place a large plate on top of the skillet. Using oven mitts, carefully invert the rosti onto the plate. Gently slide the rosti back into the pan and cook until firm and browned on the bottom, about 10 minutes more.
Let rest for 5 minutes. Cut into wedges. Serve with the sour cream and chives.