Prepare the ingredients: peel onions, garlic, galangal, fresh ginger, lemongrass, and cut a few dried red chilies.
Blend the prepared ingredients with one large onion, 6 cloves of garlic, 1 inch of galangal, 1 inch of fresh ginger, 2 stalks of lemongrass in a blender.
Add 1/2 cup of dried chili and water to blend. Blend until smooth.
Heat a wok or pan and add oil; sauté the blended mixture until fragrant and the oil separates from the ingredients.
Add 1 tablespoon of brown sugar, salt, and togarasei to taste. Continue frying until the sauce thickens into a creamy consistency.
Prepare the fish: season the tilapia with the prepared sambal and some salt and serbu aji na moto (a type of seasoning).
Wrap the seasoned fish in banana leaves. Place the wrapped fish on low heat, cover, and cook for about 15-20 minutes.
Serve when done.