This is the sauce that I bought from NTUC.
Recipe for Portuguese Steamed Fish
500g whole fish (I used Song Fish and Leather Jacket fillets)
2 stalks lemon grass, bruised and cut into 1/3 lengths
Some shallots, sliced
Chilli Padi (if you want it more spicy, sauce is already spicy by default)
Steam fish with some ginger to get rid of smell for about 7 minutes.
Get rid of water and ginger.
Pour sauce over together with lemongrass, shallots and chilli padi and steam for another 5-10 minutes till fish is cooked and tender.