8ouncesbeetsabout 1 large, trimmed, scrubbed and peeled
8ouncescelery rootabout half of one large celery root, scrubbed and peeled
Freshly ground pepper to taste
Sea salt flakessuch as Maldon, for sprinkling
Make the Beet and Celery Root Cakes: Using the large holes on a box grater or the grater function of your food processor, grate beets, celery root and onion.
Crack eggs into a large bowl and beat lightly. Add grated vegetables, flour, cumin, coriander, salt and a few grinds of pepper. Stir to combine.
Heat 3 tablespoons of olive oil in a large nonstick skillet over medium heat until shimmering. Add ¼ cup of mixture to the pan at a time, pressing down slightly with the back of the measuring cup to flatten into ½-¾ inch thick cakes. You should be able to fit 6 cakes in the skillet at a time. Cook until golden brown, crisp and cooked through, about 8 minutes total, flipping cakes occasionally. Lower the heat as necessary if the cakes are browning too quickly.
Transfer to a paper towel lined plate. Sprinkle with sea salt flakes.
Wipe out skillet and add the remaining 3 tablespoons of olive oil. Repeat the process with the remaining mixture.
Assemble the Smørrebrød: Transfer bread slices to a work surface. Spread with butter.
Place a small handful of arugula on each slice of bread.