Gather the grated vegetables in a clean kitchen towel or nut milk bag, and squeeze out as much liquid as possible until the mixture feels dry.
In a large bowl, combine the drained vegetables with the egg, flour, scallions, salt, and pepper. Stir until evenly mixed.
Heat a large skillet over medium heat and add enough oil to coat the bottom. Working in batches, scoop about 2 tablespoons of the mixture into your hands, form into small patties, and carefully place them in the skillet.
Cook the fritters until golden brown and crisp, about 1 ½ minutes per side. Transfer to a wire rack set over a baking sheet to cool slightly and drain any excess oil.
Serve warm, topped with sour cream, grated tomato, chopped scallions, and a drizzle of olive oil. Enjoy immediately.