Coarsely grate potato, turnip, parsnip, and zucchini. In small batches, take handfuls of the mixture and squeeze out excess liquid into the sink. In a large bowl, combine bread crumbs, flour, salt, and pepper.
Mix in grated vegetables, cheddar, bacon, and leek, reserving some bacon and cheddar for garnish.
Crack one egg into the mixture at a time, mixing until loose patties can be formed. Carefully drop a handful of vegetable mixture into a greased skillet over medium-high heat and flatten out with spatula. Cook in batches, spaced 1 inch apart, 3 to 4 minutes per side, or until golden-brown and crispy.
Top with extra crumbled bacon, cheddar, sour cream, or applesauce, if desired.
Vegetables listed in this recipe can be mixed and matched depending on what you have on hand. Colby jack or Swiss cheese could be used in place of cheddar.
Per serving: 402 calories, 16.5 grams fat (5.5 grams saturated fat), 156 milligrams cholesterol, 1,099 milligrams sodium, 39 grams total carbohydrates, 5 grams fiber, 24 grams protein.