Steps

• 1

  Make the burger sauce: In a medium bowl, stir together the BBQ sauce, 1/4 cup of the mayonnaise, the chopped pickles, and 2 tablespoons of the yellow mustard in a medium bowl. Season with salt and pepper and set the burger sauce aside.

• 2

  Heat all three zones on the flat top grill to medium for 10 minutes. Have handy a rimmed baking sheet.

• 3

  In a small bowl, mix the 2 tablespoons of mayonnaise with the 2 tablespoons of yellow mustard. Divide the ground beef among the tortillas. Leaving a 1/4-inch border around the edges of the tortillas, flatten the beef onto the tortillas. Season well with salt and pepper then spread the mayo-mustard mustard evenly over the meat.

• 4

  Drizzle or squirt about 1 tablespoon oil over 1 zone and use a spatula to spread it evenly. Place the onions on the hot oil, season with salt and pepper, and cook until browned and charred in spots on one side, about 2 minutes. Flip and cook until the second side is deeply browned and charred in spots and the onion rounds are tender, about 2 additional minutes. Transfer to a plate and set aside.

• 5

  Meanwhile, drizzle or squirt the remaining 2 tablespoons of oil over the other 2 heated zones then use a wide metal spatula to spread the oil in a thin layer. Arrange the tortillas meat-side down, press down on the tortillas with the spatula, and cook until the meat is deeply browned, about 1 1/2 minutes.

• 6

  Flip the tortillas over. Sprinkle the meat evenly with the shredded cheese, cover with the inverted baking sheet, and cook until the underside of the tortilla is browned and lightly crispy and the cheese is melted, another 2 to 3 minutes. Transfer to a large platter or baking sheet.

• 7

  Top the taco burgers with a generous smear of the burger sauce, the griddled onions, shredded lettuce, sliced pickles, and tomatoes. Serve immediately with any remaining burger sauce. Enjoy!