Mix the soy sauce, oyster sauce, cornstarch, and ½ cup water in a small bowl. Set aside.
Heat a wok or large pan over medium heat. Add the pork and a little water, breaking up the pork as it cooks. Once the water evaporates, let it brown, adding a little oil if needed. Season lightly with salt and pepper, then push to one side.
Add the onion and garlic, then cook until softened. Add the tomatoes and cook until soft and starting to caramelize. Stir everything together.
Add the ampalaya and cook for about 3 minutes, until slightly softened.
Push everything to the sides. Add a little oil to the center, then pour in the eggs. Let them begin to set, then gently scramble and mix with the ampalaya.
Stir the sauce again, then pour it into the pan. Toss and simmer until thickened. Taste and adjust the seasoning, then serve with rice.
Notes
Ampalaya: Choose firm, green ones. For less bitterness, salt the slices for 15 minutes, rinse well, and gently squeeze out excess water.
Ground pork: Substitute ground chicken or beef, shrimp, or tofu.
Tomatoes: Use ripe ones and cook until soft and starting to caramelize.