Caramelized Onion, Mushroom, Steak and Gruyere Dip

Football season is back in full swing, which means one thing for food lovers: tailgating! Make this amazing caramelized onion, mushroom, steak and Gruyere dish ahead of time and reheat it on the grill as the coals heat up.  Serve it with grilled bread brushed with a garlic clove or your favorite crackers.

You certainly don't need to tailgate to make this delicious dip though.  Make it for game day from the comfort of your own home.

If you don't have the cast iron skillet, just sear the steak and mushrooms in a different pan (NOT a nonstick pan, however) on the stovetop and bake everything in a casserole dish.

Caramelized Onion, Mushroom, Steak & Gruyere Dip
Serves 6-8

Ingredients
2 onions, sliced
2 tablespoons butter, divided
2 tablespoon olive oil, divided
2 tablespoon balsamic vinegar
1 clove garlic, minced
1/2 lb of sirloin, flatiron or fajita steak
2 cups sliced mushrooms
4 oz cream cheese, at room temperature
6 oz grated Gruyere cheese, divided 
1/2 cup sour cream
Salt and pepper, to taste
Grilled bread, crostini or your favorite crackers

Instructions
Heat 1 tablespoon of the butter and 1 tablespoon of the oil in a large nonstick skillet over medium heat.  Add the sliced onions and a generous sprinkle of salt.  Cook the onions until softened and just beginning to brown.  Reduce the heat to low and cover the pot.  Continue to cook the onions over low heat until they are caramelized, about 45 minutes, stirring every 10 minutes or so to prevent burning.  When they have shrunk in size significantly and turned a deep brown color, they've finished.  Add the balsamic and garlic.  Turn the heat to medium and cook, stirring often, until there is no longer any liquid in the pan, about 3 minutes. Remove the onions from the heat.

Heat a 10-inch cast iron skillet over medium-high heat.  Add the remaining 1 tablespoon of oil and swirl to coat the pan.  Season the steak with salt and pepper, and sear in the hot pan until cooked to desired level of doneness. Remove from the pan and let rest.  Add the remaining 1 tablespoon of butter and swirl to coat the pan.  Add the mushrooms and cook over medium heat until browned, about 5 minutes.  Slice the steak into 1/2 inch pieces.

Preheat the oven to 400 degrees.  In a large bowl, combine the cream cheese, half of the Gruyere and the sour cream.  Add a generous sprinkle of salt and a few cracks of black pepper, to taste.  Add the onions, mushrooms and steak, mixing to combine.  Put the mixture into the cast iron skillet and top with the remaining cheese.  Bake for about 25 minutes, until the top is golden brown.  

Serve with grilled bread, crostini or crackers.