Heat
the olive oil in a large skillet over medium-low heat. Add the onions and
cook until soft and translucent about 10 to 15 minutes. Add the sugar, red
wine vinegar and 3 tablespoons water and cook until the liquid is reduced
completely and the onions are caramelized, about 10 minutes. Set aside.

Butter
the outside of each slice of bread and arrange, butter side down, on a sheet
pan. Put 1 piece of gorgonzola onto the buttered bread, and top with thinly
sliced filet mignon. Top with a heaping tablespoon of the onion jam. Top with
equal amounts of Gorgonzola. Cover it another slice of bread, buttered side
up. Repeat with remaining ingredients.

Heat
a large skillet over medium-low heat. Put the sandwiches into the skillet and
cook until the bread is toasted and golden and cheese is melted, about 4
minutes per side. Slice each sandwich in half and serve.

Serves: 4