Ingredients: Burger Sauce - 1/4 cup mayonnaise - 2 Tbsp. ketchup - 1 Tbsp. sweet pickle relish - 1 Tbsp. yellow mustard - 1 tsp. hot sauce Smash Burger Tacos - 1 lb. ground beef - 6 (5") flour tortillas - 2 tsp. store-bought or homemade burger seasoning - Kosher salt - 6 Tbsp. neutral oil, divided - 6 slices American cheese, divided - 18 thin bread-and-butter pickle slices - 1 cup shredded iceberg lettuce - 3 Tbsp. chopped yellow onion - White sesame seeds, for serving Directions S Burger Sauce Step 1 - In a small bowl, mix mayonnaise, ketchup, relish, mustard, and hot sauce until combined. Step 2 - Make Ahead: Sauce can be made 3 days ahead. Cover bowl and refrigerate. Smash Burger Tacos Step 1 - Divide beef into 6 portions about 2 1/2 ounces each. Top each tortilla with a portion of beef. Using a fork, flatten beef on top of tortilla into an even layer, leaving a 1/2" border. Sprinkle with 1/2 teaspoon burger seasoning; season with a pinch of salt. Step 2 - In a large skillet over medium-high heat, heat 2 tablespoons oil and swirl pan to coat. Arrange 2 tacos beef side down and press into skillet to flatten with a sturdy spatula or burger press. Cook, undisturbed, until beef is browned and cooked through, 2 to 3 minutes. Flip tacos, top each with a slice of cheese, and cook until cheese is slightly melty, about 1 minute more. Transfer to a baking sheet. Repeat with remaining 4 burger tacos. Step 3 - Top each taco with burger sauce, pickles, lettuce, onion, and sesame seeds.