Cardillong Isda is an old Filipino dish that is very popular due to its simple preparation and availability of ingredients. In the Philippines, it is a way to re-cook left-over fried fish. But whether using leftover or not, fish is fried beforehand to prevent from falling apart while cooking in the sauce. Cardillo is almost similar to Sarciado. The difference between the two is that Cardillo contains srambled eggs mixed to the sauce while Sarciado is cooked without the eggs. In both dishes, fried fish is simmered in a sauce which consists mainly of garlic, onions, ginger & tomatoes. The secret to a good cardillo or sarciadong isda is to use the same oil (where you fried the fish) in sautéing, so that all the other ingredients can absorb the fish flavor.