Bring a large pot of salted water to a boil. Add the cheese tortellini and cook according to package instructions, about 2-4 minutes. Drain and set aside, coating with olive oil to prevent sticking.

In a large skillet, heat olive oil over medium-high heat. Sear the beef sirloin for about 5 minutes until browned. Remove and set aside.

In the same skillet, add more oil if needed and sauté diced bell pepper, onion, and minced garlic for 5-7 minutes until softened. Return beef to skillet and combine.

In a medium saucepan, melt butter over medium heat. Whisk in flour until golden for a minute. This is your roux.

Gradually pour in the milk while whisking to avoid lumps. Stir until thickened, about 3-4 minutes.

Reduce heat to low and stir in provolone and Parmesan cheese until melted. Adjust seasoning.

Mix cooked tortellini and beef with vegetables into the cheese sauce, stirring gently for 2-3 minutes until well-coated.

Serve hot, garnished with parsley or extra Parmesan as desired.