Try these delicious burgers that taste like you spent hours in the kitchen! Blue cheese adds complexity, while caramelized onions and mustard add sweet and spicy notes. Lettuce and tomato make the burgers juicier and bring in that satisfying crunch.
Put one patty on a microwave-safe dish and cover with a clean paper towel. Cook on HIGH for 75 seconds (times may vary depending on your appliance). Repeat until you cook the desired amount of patties.
While the patties are cooking preheat a large frying pan on medium heat and melt half of the butter. Saute the onions in melted butter until caramelized 2-3 minutes, turning occasionally. Remove from the pan and set aside.
Wipe the cooking pan with a paper towel and melt the rest of the butter on medium heat. Put pretzel buns cut side down and leave on the pan until the edges are golden brown, approximately 2 minutes. Remove from the pan and set aside.
Mix mayonnaise with dijon mustard to make the mustard sauce.
Smooth 1 tbsp of mustard sauce over both halves of the pretzel bun and assemble the burgers by layering the cooked beef patty, caramelized onions, 1 tbsp blue cheese, 2 thin tomato slices, and 1/4 cup of torn iceberg lettuce leaves.