1. Preparation: 

Cut the steak into small pieces, prepare 1 portion of shell pasta, slice the bell peppers (into pieces), dice the onion, chop the rosemary, and mince the garlic. Have the required amounts of butter, salt, black pepper, and Italian pasta sauce (optional) ready.

2. Cooking the pasta: 

Follow the package instructions to cook the shell pasta until it is 80% done (leaving a few hard cores), remove it, rinse it under cold water, and drain it.

3. Grilling the steak: 

Season the steak pieces with salt, black pepper, and rosemary for 10 minutes. Heat the pan, melt the butter, add the steak pieces and cook until you reach your desired doneness (e.g., medium rare takes about 2 minutes per side). Remove and set aside.

4. Mixing and seasoning: 

Leave the original pan with the remaining oil. Sauté the garlic, onion, and bell peppers until fragrant. Add a little Italian pasta sauce (or tomato sauce) and stir. Pour in the pasta and steak pieces and mix well. Add a little salt and black pepper for seasoning.

5. Finishing and serving: 

Once done, grind the black pepper and rosemary together to enhance the flavor.