Onions, burger, cheese and mayo. Cannot be anything special, right? But it is and you will love it. Sadly this photo is shit, and does not do it any justice, but these burgers are fantastic. If you are a champion, do your own buns.
I prefer a single patty (90-100g). You gonna need something to smash the burgers, potato masher dressed in alu-foil is a good idea. For extra points serve with the best crispy potatoes.
People will love you, I love everyone who did these for me. Experiment with the sauces.