In a bowl, mix together the 2 pounds of pig blood and about 1/4 cup of vinegar. Stir it well.

Heat oil in a big pot (or Dutch oven) on medium heat and sauté the onions, ginger, garlic, and bay leaves for 2 to 3 minutes, till the onions are translucent.

Add the 4 lbs. of pork belly and sauté until lightly browned - about 5 minutes. Add 2 tablespoons of fish sauce and continue sautéing for another 2 minutes.

Add 1.5 cups of vinegar, and bring to a boil without stirring. Continue to cook uncovered without stirring, for about 5 minutes, so that some of the vinegar gets boiled off.

Then add 2 cups of water and bring this to a boil. Once it starts boiling, cover with a lid, turn down the heat to the lowest possible, and let it simmer for 30 minutes or until the meat is tender.

Add in the mixture of pig's blood (with 1/4 cup vinegar) from before, while whisking to avoid lumps forming.

Mix in 1/3 cup of brown sugar, 4 pieces of siling pangsigang. and 1 tsp oregano. Lower the heat to low and continue simmering (with the lid off) for 15 minutes, or until the sauce is thickened. Season with salt and black pepper to taste. I add about 1 tbsp. of salt and 1 tsp of ground black pepper.

Serve over some freshly steamed jasmine rice, and puto if you have! Garnish with slices of siling pangsigang. Enjoy!