Cook Tortellini: Prepare the tortellini according to the package instructions. Once cooked, drain and set aside.

In a large skillet, heat olive oil over medium-high heat. Add the thinly sliced beef sirloin and cook until browned, about 5 minutes. Remove from the skillet and set aside.

In the same skillet, add sliced green bell pepper, sliced onion, and minced garlic. Cook until the vegetables are softened, about 5-7 minutes. Remove from heat and set aside with the beef.

In a separate saucepan, melt butter over medium heat.

Whisk in all-purpose flour and cook for about 1 minute to form a roux (thickening agent).

Gradually pour in the whole milk, whisking constantly to prevent lumps. Stir until the mixture thickens and begins to bubble, about 3-4 minutes.

Stir in shredded provolone cheese and grated Parmesan cheese. Continue stirring until the cheese melts smoothly into the sauce. Season with salt and pepper to taste.

Add the cooked tortellini, browned beef, and sautéed vegetables into the creamy provolone sauce. Stir gently to combine and coat the ingredients in the sauce.

Transfer to a serving dish and enjoy hot. Garnish with fresh parsley or additional Parmesan cheese, if desired.