Preheat oven to 400°F and line a baking sheet with parchment paper.
Peel and shred the sweet potatoes using a box grater, then squeeze out all excess moisture using a clean kitchen towel.
In a large bowl, whisk the egg and then stir in the shredded sweet potato, nutritional yeast, hemp seeds, rosemary, thyme, garlic powder, onion powder, salt, and pepper.
Scoop about one tablespoon of the mixture at a time and shape into small cylinders, placing them on the prepared baking sheet.
Bake for 22 minutes, flipping halfway through, until the edges are golden brown and crisp.
While the tots bake, whisk together the Greek yogurt, lemon juice, and minced chives in a small bowl to create the dipping sauce.
Serve the warm tots immediately with the chilled herb dip.