Ingredients

2 tsp	olive oil		10 mL
1 1/2	red onions, thinly sliced		220 g
1 tbsp	wine vinegar		15 mL
2 tsp	brown sugar		8 g
3/4 tsp	caraway seeds		1 g
4	chicken sausages, smoked		150 g
8 slices	rye bread		160 g
4 tsp	Dijon mustard		20 mL
40 g	Gruyère cheese, thinly sliced
1/2 tbsp	butter, unsalted		7 g
	salt to taste
	ground pepper to taste

Method

1. Heat the oil in a skillet over medium heat. Thinly slice the onions, add them to the skillet, and sauté until slightly softened about 4 min. Stir in the vinegar, brown sugar, and caraway seeds. Lower the heat to medium-low and sauté the onions until very tender, about 15-20 min longer. Add salt and pepper.
2. Put the sausages on a medium-hot grill and cook until brown and crisp, about 3 min per side. Alternatively, broil them in the oven. Transfer the sausages to a working surface and cut them in half lengthwise. For each sandwich, arrange 2 halves of sausage on a slice of bread. Spread about 1 teaspoon of mustard on each sausage layer, then top with the caramelised onions, dividing them equally among the sandwiches. Thinly slice the Gruyère cheese, then distribute the slices on top of the onions. Cover each sandwich with the remaining bread slices. Spread half of the butter over the top of each sandwich.
3. Heat a nonstick, heavy-bottom pan over medium-low heat. Carefully put the sandwiches, buttered side down, in the pan. Cover and cook about 3 min, until the bottoms are brown. Spread the remaining butter over the upper bread slices. Turn the sandwiches and cook until the bottoms are brown, 2-3 min longer.
4. Serve.