Trim excess fat from the meat. It will still be marbled, and that's fine, but you don't want a big chunk on the edge.

Mix flour with salt and pepper.

Rub the seasoned flour into the meat,and pound it in, so the meat is well coated.

Heat the oil in a large heavy frying pan. Brown the meat in the oil, 3-5 minutes on a side, until it is well browned. Add onions, stir in oil, cook until starting to soften.

Add tomatoes. Bring to a low boil, then lower heat to a simmer.

Simmer over low heat for an hour and a half - 2 hours (for a larger piece of meat.)