1. Chop the onion
2. Put the oil, onion, and ground beef in the pot. Sauté until the meat changes color.
3. Add the pasta, tomato pulp, tomato sauce, ketchup, mustard, broth, and water. Mix well.
4. The water should reach the level of the pasta, adjust if necessary according to your pasta.
5. Cook under pressure for 5 minutes (half the time indicated on your pasta package).
6. At the end of cooking, add the cheese and chives. Mix well. Close the lid for 2 minutes so that the cheese can melt completely. Mix again and serve.
7. Enjoy your meal!