Heat a large pot of water over high heat, add noodles, and cook according to package directions. Drain well and transfer to a medium bowl.  Add eggs, onion, matzah meal, caraway seeds, and salt. Stir well to combine. Line a sheet pan with two layers of paper towels. Heat ¼-inch oil in a large sauté pan over medium heat.  Working in batches, carefully pack ½ cup noodle mixture into 3 ½-inch round cookie cutters or ring molds in the pan and fry for 3 minutes. Using tongs, remove from molds, flip and fry another 3 minutes or until nicely browned. Drain on the prepared pan, and continue with remaining noodle mixture. While frying noodle cakes, sauté red cabbage, sugar, and vinegar in a small sauté pan over medium-high heat until wilted , about 6 to 8 minutes. In a small bowl, combine sour cream with horseradish to taste, if desired. To serve, place each cake on an appetizer plate. Top each cake with a little cabbage and a dollop of sour cream. Serve immediately.