In a deep pot, place pork belly, enough water to cover, and salt and pepper to taste. Bring to boil, skimming scum that floats on top.
Lower heat, cover, and cook for about 40 to 50 minutes or until tender but not falling apart.
Drain pork well and reserve ½ cup of broth.
Place pork on a wire rack over a baking sheet. Refrigerate, uncovered, for at least 4 hours or overnight until completely cold.
In a wide, deep pan, heat about 2 inches deep of oil. Carefully add cooled pork in a single layer. Cook until golden and crispy, turning on sides as needed.
Remove the pork from the pan and drain on a wire rack. Cut into small pieces.
In another pan, heat 1 tablespoon of oil. Add the chopped onions and garlic and cook until softened.
Add tomatoes and cook, mashing with the back of the spoon, until softened and release juice.
Add shrimp paste. Cook, stirring regularly, for about 1 to 2 minutes.
Add vinegar and bring to a boil, uncovered and without stirring, for about 1 to 2 minutes.
Add the reserved pork broth and bring to a boil. Lower heat and continue to cook for about 3 to 5 minutes or until slightly thickened. Season with salt and pepper as needed.
Add fried pork and lightly toss until just coated with sauce.
While the binagoongan is cooking, steam eggplants. Discard stems and cut into cubes.
Arrange pork binagoongan on a serving platter. Top with steamed eggplant, diced mango, diced tomatoes, diced onions, and green onions. Serve immediately.