Slice the flank steak into thin strips and season with salt and pepper. Heat olive oil in a large skillet over medium-high heat, add steak, and cook for 3-4 minutes until browned. Remove and set aside.
In a pot, bring salted water to a boil, add tortellini, and cook for 3-5 minutes until al dente. Drain and set aside.
In the same skillet, sauté minced garlic for 1 minute. Add heavy cream, beef broth, and Italian seasoning. Bring to a simmer and stir in Parmesan cheese until melted and smooth.
Add cooked tortellini and steak back into the skillet, toss to coat in the sauce, and heat through for 2-3 minutes.