Peel and halve the onions and cut into fine strips.
Heat the oil in the pan, add the onions and cook on a low heat for 10-15 minutes with the lid closed. Stir occasionally. Add balsamic vinegar, honey, thyme sprigs, bay leaf, salt and pepper to the onions and cook for another 5-10 minutes.
For the bit burgers:
Divide the ground beef into four portions. Place each portion in a round cookie cutter and flatten it to make hamburger patties. Heat the oil in a pan and fry the patties on both sides. Salt and pepper.
Toast hamburger buns in the oven. Cover both halves with a lettuce leaf. The top half also gets a slice of tomato. The lower half is used for the fried hamburger pattie. Now pile a generous portion of onion jam on the pattie and serve the two bun sides open on a plate.
This goes well with Don Diego`s Nat King Cole Slaw and - logically - a fresh, cool, tart, light bit.