Needing a way to make use of a loaf of rye bread, I came across this from Smitten Kitchen. This is an amazing, gooey grilled cheese sandwich. If you like rye, you need to get on this.
1 tbsp olive oil
1 tbsp unsalted butter
1 large red onion, halved and thinly sliced, yields about 2 cups
2 tsp brown sugar
1/4 tsp table salt
1 tbsp balsamic
plenty of freshly ground black pepper
4 sliced rye bread
2/3 cups grated Swiss cheese
Heat the oil and butter over medium high heat in a large skillet. Add the onion and cook for 5 minutes. Add in the brown sugar and lower the heat to medium low. Continue to cook until the onions become incredibly soft and cooked down, between 10 and 15 minutes. Add in the vinegar and scrape the bottom to remove those tasty bits. Continue to cook for another 2 minutes and season with black pepper. Let cool to lukewarm.
Butter the outside of each slice of butter. Place a few tablespoons of swiss cheese, top with two tablespoons of the onion jam and top with a few more tablespoons of swiss cheese. Top with another slice of bread.
Heat a skillet over medium high heat and place the sandwiches in the pan. Cook about 5 minutes on each side, until golden brown and the cheese melts.