01 -
Roll the ground chuck into about 1/3-pound balls, then let them chill in the fridge for half an hour.
02 -
Use a mandoline to cut the onions into super-thin slices, squeeze out any excess liquid, and store them in the fridge.
03 -
Cook the bacon until it’s crunchy, then chop it into smaller bits and set aside.
04 -
Combine the mayo, ketchup, mustard, chopped bacon, Worcestershire, vinegar, seasoning blend, and chili flakes. Keep it chilled until needed.
05 -
Preheat your griddle, spread some oil, place meatballs on it, pile sliced onions on top, and smash them flat. Add seasoning and cook for 3 to 4 minutes.
06 -
Squirt mustard on top, flip the patties, lay the cheese slices on, and let it melt for around 3 minutes.
07 -
Toast the buns, spread sauce on each side, layer on two patties, add more sauce on top, and cover with the bun lid.