“MAC” SAUCE 1/4 lg white onion 1/3 c mayonnaise 3 Tbsp sweet pickle relish 1 Tbsp distilled white vinegar 1 1/2 tsp yellow mustard 1 1/2 tsp ketchup 1/2 tsp turmeric BURGERS iceberg lettuce 4 brioche buns, split 8 Tbsp butter, divided 8 Tbsp “Mac” sauce white onion sliced kosher dill pickles 12 oz hamburger…