The classic cold cut sandwich is popular with diners and many chain restaurants. This style of sandwich is fairly simple, made with slices of cold cuts and veggies. These sandwiches can be customized with all your favorite toppings and can be eaten hot or cold.
Saute the Onions: Place a large skillet over medium heat. Add the oil and onions. Sauté for 10 to 12 minutes stirring regularly, adding the balsamic vinegar halfway through to prevent sticking. Once the onions are nicely brown and caramelized, remove from heat.
Prepare to Assemble: Set up an assembly station by laying out the cold cuts, cheese slices, arugula, sliced tomato, onions, sauce and buns.
Toast the Buns: Preheat the oven or griddle to 350°F. Brush the buns lightly with olive oil. Then put them in the hot oven or griddle for 2 to 3 minutes.
Assembly: Spread the optional horseradish cream sauce onto the bottom buns. Sprinkle on some arugula or greens. Add several slices of cold cuts followed by some salt and pepper. Layer on the caramelized onions, cheese, tomatoes and a few more greens. Add the tops of the buns and serve.