Preheat the oven to 400 degrees F. Slice the potato into 1/4 inch thick pieces using a large sharp knife and cutting board. Place a piece of parchment paper on a sheet pan and lay the slices on the parchment paper in a single layer. Drizzle the avocado oil on the sweet potato and sprinkle the salt on top as well, then rub both sides of each sliced with your hands to coat. Stick the sheet pan in the oven and set the timer to 20 minutes. When it goes off, use a spatula to flip the sweet potato slices and cook another 20 minutes, or until they’re cooked but not overly soft.
Place the ground beef in a large bowl. Measure out and dump in the kosher salt, ground black pepper, garlic powder, dried minced onion, coconut aminos, and fish sauce. Before mixing everything together, take a skillet out and place it on a burner over medium heat. Then combine ingredients together with your hands until the spices and liquids are evenly distributed. Separate the ground beef mixture into 6 equally sized portions in the bowl.
Take the first portion and form it into a small hamburger patty using your hands - it should be roughly half an inch thick and 3 or so inches wide. Press your thumb in the middle of the patty to make a small dent in the top, then place it (with the dent side up) in the skillet. You can also put the dent in the patty once it’s in the skillet if you forget to do it before. Repeat the process with the remaining 5 portions of meat.
Cook the patties on one side for 4 to 5 minutes, then flip them over with a spatula and cook another 3 to 4 minutes on the second side. When they’re done, place them on a paper towel lined plate to remove any excess grease.
When the sweet potatoes are done, take them out and let cool slightly. Then assemble the burgers by placing a hamburger patty on top of one sweet potato slice and top with a slice of tomato, 1/6 cup guacamole, and 1/2 tbsp of ranch dressing. You can serve open faced or top with another slice of sweet potato.