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

Cook Beef: 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.
Cook Vegetables: 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.

Melt Butter: In a separate saucepan, melt butter over medium heat.
Make Roux: Whisk in all-purpose flour and cook for about 1 minute to form a roux (thickening agent).
Add Milk: Gradually pour in the whole milk, whisking constantly to prevent lumps. Stir until the mixture thickens and begins to bubble about 3-4 minutes.
Add Cheese: 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.

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