Preheat the oven to 400 degrees Fahrenheit. Scrub the sweet potatoes and prick them all over with a fork. Wrap each potato in aluminum foil and bake in the preheated oven for 60 minutes.
Meanwhile, saute the green chile and onion together over medium heat in a drizzle of oil until caramelized. Season lightly with salt.
Combine the cooked chile and onion in a large bowl with the turkey, garlic powder, salt, and pepper. Shape the meat mixture into 12-14 patties.
Cook the patties in a skillet over medium heat in a drizzle of oil for 4-5 minutes, or until browned. Flip and repeat.
Slice the cooked sweet potatoes into rounds, being careful not to smash the flesh. Scrape up any drippings from the sausage and add a little more oil to the skillet. Cook the sweet potatoes in the skillet until caramelized, about 3 minutes per side.
Top each sweet potato slice with a sausage patty and avocado. Sandwich with a second sweet potato slice. Serve.