1. Preheat oven to 400℉. Generously spray a large baking sheet with cooking spray. 2. In a food processor in 2 batches, pulse broccoli until very finely chopped (alternatively, finely chop broccoli with a knife) and transfer to a medium bowl. 3. Add Cheddar, sweet potato, eggs, bread crumbs, oregano, 1 teaspoon garlic powder, onion powder, and ½ teaspoon salt and stir well to combine. Use your hands to make sure the mixture is thoroughly mixed. 4. To shape each tot, use a heaping tablespoon of the mixture, and squeeze in your hand to compact it well. Form into an oblong tot shape by pressing gently on the ends. Place on prepared baking sheet. 5. Bake until browned on the bottom, about 15 minutes. Use a metal spatula to flip tots and bake 15 minutes more. 6. While tots bake, prepare dipping sauce: In a medium bowl whisk to combine sour cream, buttermilk, dill, chives, lemon juice, remaining 1 teaspoon garlic powder, and remaining ½ teaspoon salt. 7. Serve tots warm with dipping sauce.