3 tablespoons bottled red taco sauce
3 tablespoons mayonnaise
2 teaspoons pickled jalapenos, minced
2 tablespoons vegetable oil, plus additional for brushing grill rack
2 large white onions
2 tablespoons sugar
2 1/2 teaspoons salt, divided
1 1/2 pounds ground chuck
1/2 pound chorizo, removed from casing, if necessary
1 clove garlic, minced
1 teaspoon cumin
3/4 teaspoon freshly ground black pepper
6 ounces queso fresco, crumbled
6 sesame seed hamburger buns
6 green leaf lettuce leaves
1 avocado, sliced
Prepare a medium-hot fire in a charcoal grill with a cover.
In a small bowl, blend together taco sauce and mayonnaise, stir in pickled jalapenos; set aside.
Heat 2 tablespoons oil in a large, fire-proof skillet on grill rack. Cut onions in half, then in half-ring slices 1/4 inch thick. Add onions to skillet and saute for 15 minutes or until onions are soft and golden brown. Add sugar and 1 teaspoon salt. Continue to cook for another 15 minutes or until onions are dark brown and caramelized. Remove skillet from heat; set aside.
In a large bowl, gently combine ground chuck, chorizo, garlic, cumin, black pepper, and remaining salt. Divide mixture into 6 equal portions and form round patties with hands.
Brush grill rack with vegetable oil. Place patties on grill, cover, and cook for 4 minutes. Turn patties over and cook an additional 4 minutes, or until done to preference. During the last few minutes of grilling top patties with queso fresco to melt, and place buns cut side down on outer edges of grill to lightly toast.
Slather taco sauce mixture on the bottom halves of the buns. To assemble burgers, layer bottom bun halves with lettuce, patties, caramelized onions, avocado slices, and bun tops.