Heat the vegetable oil in a large skillet over medium heat. Add the chopped onion and sauté until translucent.
Stir in the minced garlic and sliced ginger, cooking for another minute until fragrant.
Add the sliced green chili peppers and cook for an additional minute.
Pour in the coconut milk and bring to a gentle simmer.
Stir in the shrimp paste and soy sauce, mixing well to combine.
Gently add the bangus fillets to the skillet, ensuring they are submerged in the sauce. Cover and simmer for about 10-15 minutes, or until the fish is cooked through.
Season with salt and pepper to taste. Remove from heat and let it sit for a few minutes to allow the flavors to meld.
Serve hot, garnished with chopped green onions over steamed rice.