Optional toppings: sliced red onions, heirloom tomatoes, hot pepper sauce and fresh cilantro leaves
In a small skillet, cook chorizo over medium heat, crumbling meat, until cooked through, 4-6 minutes. Drain and cool slightly. Combine chorizo with cheese, cilantro, garlic and jalapeno.
Shape ground beef into twelve 1/4-in.-thick patties. Spread chorizo mixture over six patties to within 1/2 in. of edges; top with remaining patties, pinching edges to seal. Refrigerate 30 minutes.
Sprinkle burgers with pepper and salt; grill, covered, on a greased rack over medium direct heat until a thermometer reads 160°, about 6-8 minutes per side. Remove from heat; tent with foil and let stand 4-5 minutes.
Meanwhile, grill buns until golden brown. Serve burgers on buns with salsa and toppings as desired.