Prepare the Pork: In a pot of boiling water, cook the pork belly until tender, about 40 minutes. Remove from the pot and allow it to cool. Once cooled, chop the pork belly into small pieces.
In a large pan or skillet, heat the cooking oil over medium heat. Sauté the minced garlic and onions until fragrant and translucent.
Add the chopped pork belly to the pan, stirring occasionally until it starts to crisp up. Add the minced red and green chili peppers, and continue cooking until the pork is crispy and golden brown.
Pour in the soy sauce and oyster sauce, stirring to coat the pork evenly. Cook for another 3 minutes to allow the flavors to meld.
Squeeze the calamansi juice over the pork sisig and stir well. Add the mayonnaise and mix until fully incorporated, creating a creamy texture. Season with salt and pepper to taste.
Transfer the Pork Sisig to a sizzling plate or serving dish. Crack the raw eggs over the sisig, if desired, and let the residual heat from the plate cook the eggs slightly. Garnish with chopped spring onions and additional chili peppers for extra flavor and presentation.
Pork Sisig is traditionally served on a hot sizzling plate to create a dramatic presentation. It is often enjoyed as an appetizer or pulutan (beer match) alongside cold beverages.
Pork Sisig can be made with other cuts of pork such as pork cheeks, pork ears, or even chicken or tofu for a different twist. Some recipes also include chopped liver for added richness.