Sliced beef (any beef is good but a steak will make it very tender)
Marinate the beef with soy sauce, lemon and pepper (for a day or so).
Boil beef with the marinade to tenderize the beef. Remove the rest of the liquid.
Add oil to pan and brown the beef and onions. Add the liquid. If marinade is too thin, you can continue to boil to thicken it.