Preheat oven to 375. Cut sweet potato into ¼ ‘’ rounds.
Place rounds on a baking sheet. Drizzle with olive oil, sprinkle with salt, and toss to coat. Roast for 30-40 minutes until soft and beginning to brown.
Meanwhile, heat a drizzle of oil in a pan. Sprinkle the meat with salt and pepper and gently mix by hand without breaking up the meat too much. Form loosely into 5 small patties.
Place patties in the pan – it should be hot enough that they sizzle. At no point should you squash the burger – keep the juices inside! Cook until the first side is well browned, then flip. Remove from pan when they are done to your liking. Place patties on top of roasted sweet potato rounds and top with sliced avocado, onion and your favorite burger topping; then top with another sweet potato slice.