Filling: Set a 12-inch sauté pan over medium heat and add the lard. Once the fat is shimmering, add the ground beef and cook, stirring, until crumbly and browned, 5–10 minutes. Taste and adjust seasoning with salt. Add the grated cheese and stir until completely melted, about three minutes. Remove from the heat.

Layout the warm tortillas on a platter. Spread a tablespoon of mayonnaise on each tortilla. Cover all but the edge of half of each tortilla with the cheeseburger filling. Serve along with bowls of toppings and salsa; let each diner add their own toppings then fold quesadilla in half.