In a medium mixing bowl, combine the ground buffalo, chili powder, smoked paprika, sea salt, black pepper, and lime juice.
Gently mix the ingredients by hand until just incorporated, ensuring you do not overwork the meat to keep the texture light.
Form the mixture into one large patty, approximately 3/4-inch thick, and create a small indentation in the center with your thumb.
Heat the olive oil in a cast-iron skillet over medium-high heat until shimmering.
Place the patty in the skillet and sear for 4-5 minutes on the first side until a dark crust forms.
Flip the burger and cook for another 4 minutes, or until the internal temperature reaches 155°F for medium doneness.
While the meat rests for 2 minutes, lightly toast the sprouted grain bun in the same skillet or a toaster.
Assemble the burger by placing the patty on the bottom bun, followed by the avocado slices, red onion, lettuce, and tomato.