Preheat the air fryer. Set to 375°F (190°C) for 5 minutes.
Preheating helps the patties sear and release easily.
Mix the base. In a bowl, whisk egg white with Greek yogurt, Worcestershire, salt, pepper, garlic powder, smoked paprika, and grated onion until smooth.
Add the meat and binder. Add the ground meat and quick oats. Gently mix with a fork or your hands just until combined. Do not overwork or the burgers will be tough.
Form patties. Divide into 4 equal portions (about 4 oz/113 g each). Shape into patties about 1/2-inch thick.
Press a small indent in the center of each to prevent puffing.
Prep the basket. Lightly spray the air fryer basket with avocado oil spray to reduce sticking.
Cook the first side. Place patties in a single layer with space between. Air fry at 375°F (190°C) for 6–7 minutes.
Flip and finish. Flip patties carefully. Air fry another 4–6 minutes, or until the internal temperature hits 160°F (71°C) for beef/turkey/chicken.
Add cheese during the last minute if using.
Rest the burgers. Let patties rest on a plate for 3–5 minutes. This keeps the juices inside.
Toast buns (optional). Briefly air fry buns cut-side up for 1–2 minutes.
Assemble and serve. Layer buns or lettuce wraps with your favorite toppings and the hot patties. Serve immediately.