For the marinade, mix together vinegar, salt, pepper, sugar, stock, onions and finally oil. Possibly add a little more water.
Lightly fry the diced pork belly in butter, add white bread cubes (slightly smaller than croutons) and roast until golden brown.
In the meantime, cover a few slices of rustic bread with butter and cheese.
Put the washed lettuce in the marinade and fold in. Pour the bacon and croutons on top and serve immediately so that the crispy ingredients don`t soften.