Marinate the ox tongue for 2-3 hours in calamansi (or lemons) and meat seasoning.
Boil the ox tongue with the marinade adding tanglad and water enough to cover the meat. Cook in 1-2 hours until the meat is little tender.
Rinse tongue in running water, clean and peel the rough skin. Store inside the refrigerator for 1-2 hours, this will make the tongue firmer and easy to slice.
Slice thinly in serving sizes.
Sauté the chopped onions and minced garlic.
Put-in the Ox Tongue and cook for a few minutes
Add the tomato puree, diced tomatoes, beef cube, sugar and water then simmer for an hour.
In a separate pan, heat the cooking oil and fry the potatoes. Set aside
On the same pan were the potatoes were fried, remove excess oil and sauté the mushroom.
Add some oyster sauce then set aside
Once the Ox tongue is tender, add salt, pepper, sliced red bell peppers and green olives.
Simmer for 5-10 minutes.
If the tongue is still not tender, transfer all to a slow cooker and cook for another 30 minutes to an hour on high heat.
Serve hot with rice.