Cut the selected meat into strips, season with pepper, cumin and salt (I put 1 or 2 pinches of each at most).
Let the meat rest for 20 minutes to refine the taste.
Add enough oil to fry a few strips (between 7 and 8). The oil needs to be very hot.
Start the frying with a few strips so that the oil doesn't turn into a soup, remove them and set aside.
Don't let it fry too much so that the meat doesn't get tough.
SAUCE:
Change the oil in the pan and sauté the grated onion.
After golden, throw all the strips of meat into the pan and stir.
Fry for 3 minutes and throw the cream, ketchup, tomato paste and mustard into the pan.
Let it boil a little, always mixing.
Serve with white rice and potatoes chips.