Add the ground beef to a mixing bowl. Mince the white root ends of the spring onions and add to the ground beef.
Separate the yolks from the egg whites. Add the whites from 2 eggs to the meat mixture. Discard the rest of the whites and set the yolks aside.
Add the breadcrumbs, a pinch of salt and freshly ground black pepper to meat mixture. Mix with your hands until homogeneous. Divide the mixture into 4 and form 4 patties by pressing the mixture onto parchment paper.
Set a non-stick frying pan on medium-high heat and cook the beef patties 2-3 minutes per side. They will release some grease, so there is no need for extra cooking fat if using a non-stick pan.
As the meat is cooking, halve the bread rolls and spread butter over open faces.
Lay cooked meat patties over butter layer. Rest for a couple of minutes so that the heat of the meat will melt the butter.
Peel and slice the onion into rings. Place a couple of rings over every beef patty. Top each sandwich with a raw egg yolk right in the centre of the onion rings.
Sprinkle some more salt and pepper and top with sliced spring onions (the leafy ends).
Notes
The nutrition information listed in this recipe is just an estimate based on a suggested serving portion.