Sear the Meat: In a large skillet, heat the olive oil over medium heat. Add the beef pieces and brown them on all sides (about 5-7 minutes). Remove the meat from the skillet and set aside.

Prepare the Sauce: In the same skillet, add the sliced onion and minced garlic. Sauté until tender (about 3-4 minutes).

Add the green pepper, beef broth, and mustard. Let simmer for 5 minutes.

Incorporate the Cream: Add the heavy cream to the skillet and mix well. Return the beef pieces to the skillet and let simmer on low heat for 10 minutes, until the meat is fully cooked and coated in sauce.

Season: Taste and season with salt if necessary.

Serving: Serve hot, garnished with fresh parsley if desired. Pair it with rice, pasta, or vegetables.