Place turkey, onion, jalapeño, and spices together in a large bowl and mix together until all the ingredients are incorporated.
Lightly wet your hands and use them to shape 4 circular patties about 4 inches (10 cm) in diameter.
Heat up about 2 tablespoons of vegetable oil in a pan over medium heat.
Cook burgers for 2 minutes on the first side, then flip, lower heat to low, and cook them for an additional 5-6 minutes. Top with pepper jack cheese during the last minute.
NOTE: The turkey burgers must be cooked through. Use a meat thermometer to check each patty for an internal temperature of at least 165˚F (75˚C) before removing from pan.
Assemble the burgers as desired with bun, bel peppers, lettuce, tomato, and preferred condiments.
Serve with Air Fryer Sweet Potato Wedges in Southwestern Seasoning