Mix the ground beef with one finely chopped onion and 4 cloves of garlic, add salt, pepper, olive oil, chili powder, and hmeli suneli seasoning. Mix well (using your hands or a mixer) to combine all the ingredients. Refrigerate for two hours.
Meanwhile, slice the burger bread. Depending on the thickness of your loaf of bread, you might want to cut the middle section out (like we did in our video below), or you can simply cut the loaf in half horizontally.
After 2 hours, remove the meat from the fridge and shape it into 1cm thick round patties, around 10 cm in diameter.
Toast the bread (both sides) on the grill with the lid open.
Grill the beef patties, approx. 1.5 min on each side, repeat 2 times (each side of the patties needs to be grilled 3 x 1.5 min; it will ensure the meat is cooked well but remains juicy). The grill temperature needs to be 150-180°C (300-350°F).
Add a droplet of teriyaki sauce on each meat patty and spread it evenly using a silicone brush (only on one side of the patty).
Top the patties with the grated cheese and close the grill lid. Allow the cheese almost (!) to melt. Then transfer the patties to a plate - the cheese will continue melting.