Preheat oven to 375°F.
Grease 13x9 baking pan.
Whisk together eggs, flour, onion, horseradish, salt and pepper until well combined.
Add in carrots, parsnips, potatoes, and sweet potatoes and mix well.
Heat cooking oil in large skillet over medium-high heat.
Ladle small piles of mixture into the skillet, press down with a spatula to form patties. Cook until patties are browned, then carefully flip and cook again until browned; remove to baking sheet and continue cooking until all mixture is used.
Bake for 12 to 14 minutes or until patties are cooked through and firm.
Serve hot.