There are many types of sambal, a thick, spicy condiment popular in Southeast Asia. This version isn't traditional - it's a hybrid of flavours I like. This recipe makes more sambal than you will need for one dish of okra, but it can be stored in the fridge for several weeks, and used to spice up other stir-fried vegetables. It's also delicious as a condiment to serve with mild dishes.
For this sambal, use Malaysian or Singaporean belacan (fermented shrimp paste), which is drier than the Thai version. Canldlenuts - a rich nut with a high fat content, which is used to thicken sambals in Malaysia and Singapore - are difficult to find. If you can't get them, substitute macadamia nuts. Look for the ingredients in shops that specialise in southeast Asian products.
Pull the stems from the dried chillies and shake out as many seeds as possible. Put the chillies in a bowl, add just enough warm water to cover and leave for 30 minutes to rehydrate. Briefly rinse the dried shrimp then put them in a bowl and cover with hot water and leave for 30 minutes. Drain the chillies, discarding the soaking liquid, and drain the shrimp but reserve the soaking liquid.
Put the belacan on a square of aluminium foil in an unoiled skillet over a medium flame. Toast it, turning it frequently, until the belacan darkens slightly, the fragrance (some would say "stench") intensifies, and it becomes dry and crumbly. Watch it carefully so it doesn't burn. Cool to room temperature.
Put the rehydrated chillies and shrimp in a blender (preferably a bullet blender), food process or mortar. Add the garlic, shallots and candlenuts (or macadamia nuts). Process or pound the ingredients into a thick, rough paste - it should not be smooth. If the mixture is too thick, add a little of the shrimp soaking liquid. Add the belacan and palm sugar and process (or pound) until just incorporated.
To make the okra, boil a large pot of salted water and blanch the vegetables for 30 seconds. Drain but do not rinse. Blot off the excess moisture with paper towels. As soon as the okra is cool enough to handle, trim and discard the stem ends. Cut the okra into 2cm ( ¾in) pieces
Heat a large wok over a high flame. Add the cooking oil and swirl to lightly coat the wok. Add the okra and a sprinkling of salt. Spread out the okra so as much as possible comes into contact with the hot metal, and let it char slightly before stirring and repeating, adding more oil, if needed. Add 80g (2⅞oz) or more of the sambal to the wok and stir to lightly coat the okra. Stir-fry for a minute or so, then taste for seasonings and correct if needed. When the okra is crisp-tender, turn off the flame. Stir in the calamansi juice and serve immediately.
Store the leftover sambal in a glass jar, levelling out the surface and covering in a thin layer of oil. It will keep for several weeks in the fridge.