In a medium mixing bowl, combine the ground chicken, Greek yogurt, smoked paprika, garlic powder, onion powder, sea salt, and black pepper.
Gently mix the ingredients by hand until just incorporated, being careful not to overwork the meat, then shape into one large, uniform patty.
Heat the avocado oil in a cast-iron or stainless steel skillet over medium-high heat until the oil begins to shimmer.
Place the chicken patty in the skillet and sear for 5 to 6 minutes on the first side until a deep golden crust forms.
Flip the burger and cook for an additional 5 minutes, or until the internal temperature reaches 165°F.
While the chicken is finishing, lightly toast the whole grain bun in a separate pan or toaster until warm and slightly crisp.
Mash the avocado onto the bottom half of the toasted bun, then layer with the butter lettuce, the seared chicken patty, and the tomato slice.
Place the top bun over the burger and serve immediately while hot.