Preheat the oven to 100°.
STEP 1
Grill or fry the burger for 1 minute and 15 seconds on each side with a little grease over medium heat.
STEP 2
Cut the buns in half and heat in the oven for a few minutes.
STEP 3
Fry the onion rings in a little fat until lightly browned.
STEP 4
Mix the mayonnaise with the mustard. Take bottom of bun, add mustard mayonnaise, pickle, burger, tomato slices, fried onion rings and a little ketchup. Top with lettuce and close with top bun.