1. Preparation: Combine ground turkey with jalapeño, red onion, chili powder, cumin, salt, egg, and breadcrumbs in a mixing bowl, mixing gently to distribute seasonings evenly without compressing the meat.
2. Patty Formation: Divide the seasoned turkey mixture into four equal patties, creating uniform thickness to ensure consistent cooking.
3. Grilling Setup: Preheat grill or grill pan to medium-high, lightly oiling the surface to prevent sticking and create appetizing sear marks.
4. Cooking Process: Place turkey patties on the heated surface, cooking undisturbed for 6-7 minutes per side until achieving a deep golden-brown crust and internal temperature of 165°F (74°C).
5. Cheese Topping: During final moments of cooking, layer pepper jack cheese over patties, covering to allow smooth melting and creating a creamy finish.
6. Assembly: Transfer cooked burgers to a plate, crown with fresh guacamole, and nestle into chosen bun – brioche or whole wheat – completing the spicy, flavorful turkey burger experience.

Caution: Handle jalapeños with gloves or wash hands thoroughly after preparation to prevent skin irritation.