Metropolitan Market's mini-hamburger buns, or you can use small dinner rolls.
Fry pancetta or bacon in a non-stick pans. I used sliced pancetta.
In a separate pan, saute sweet onions in a pan with olive oil until soft and golden.
I used Kobe beef but any ground sirloin (or hamburger) will do…not too lean or it won't be juicy! I used a small cookie scooper to make balls the size of a golf ball and shaped into a hamburger patty. Seasoned with freshly ground pepper. Because I fried the burgers in the pancetta/bacon grease left over in the pan, I didn't add any salt.
Fry patties for just a few minutes on each side until they start to brown.
Split buns and add just a light spread of butter. Put under broiler until golden.
Spread dijon mustard on the buns.
Add a burger with some grilled onions.
Top with cheese. I had a nice blue and a manchego as options (I used blue).
Then add a piece of pancetta (or bacon) cut to fit on the mini burger.
Sliced tomato or lettuce are optional…I decided to skip it on these little morsels.