My mother wanted to eat bistek tagalog but we didn't have any beef in the freezer. I used the next best thing to accommodate her request i.e. I used pork tenderloin instead. It actually tastes great.
Slice 500 grams of pork tenderloin into thin strips and marinate the pork in equal parts of soy sauce and calamansi for an hour. In this case, it's 1/4 cup each. Then fry the pork pieces in oil till they brown and remove it from the pan. Arrange the pork strips on a serving platter. Fry slices of a large onion in the same oil on which you cooked the pork. Arrange the cooked onions on the platter of cooked pork. Pour the marinade into the hot oil and simmer the it for a few minutes to make a sauce. When done, pour the sauce on the fried pork and onions. Serve hot.