Heat the oil in a large pan and brown the meat in small batches, transferring the browned meat to a bowl while you do the next batch. When all the meat has been browned well, tip it all back into the pan. Add the onion and cook for a few minutes before pouring in the beef stock.
Turn down the heat to low, cover and simmer for 2-2 1/2 hours. I often do this the day before to allow the flavours to develop.