4 170 gram boneless cuts of beef, top round/sirloin/flat iron
4 tablespoons olive oil
Salt and pepper to taste
1 teaspoon fresh thyme
1 tablespoon cornstarch (or flour)
1/2 cup grated gruyere
1/2 cup grated mozzarella
1/4 cup shredded Parmesan cheese
Chopped fresh parsley to garnish
Preheat an oven to 400 degrees and drizzle the beef with olive oil, and season with salt, pepper, and fresh thyme.
Heat a cast iron skillet over medium-high heat. Sear the beef on both sides until nice and golden about five minutes. Remove and set aside.
Add butter to skillet and let melt. Add sliced onions and stir. Season liberally with salt and stir. Continue to cook, stirring often, for about 15 minutes or until onions are translucent and soft.
Sprinkle the cornstarch over onions and incorporated with a wooden spoon. Pour in beef broth and use a whisk to stir the mixture and make sure the cornstarch is completely dissolved.
Once the broth starts to thicken add the beef back into skillet and spoon over sauce. Top with half the cheese and fire into the oven and cook for five to eight minutes, add the remaining cheese and melt.
Spoon sauce and onions over the beef. Garnish with parsley and crusty bread. Serve.