Soak the buah keluak in room temperature water for 5 days. Change the water every day. Place a side plate over the buah keluak to hold them down, as they'll float to the top otherwise.
On the 4th Day (Optional)
Drain the buah keluak, and brush them all over with a stiff vegetable brush. Rinse, top with water, and leave to soak another day.
Cooking Day
Drain the buah keluak, and brush them again, getting rid of any sign of ash, which will be a lighter colour. Rinse, and set aside.
Marinate the Chicken
Sprinkle 1/4 tsp of turmeric and ¼ tsp salt all over the chicken and rub in well. Cover and set aside until needed.
Spice Paste
Peel and quarter the onion, and drop 1 quarter piece into the chopper. If using mortar, leave out the onion for now.Peel and slice the galangal and drop into the chopper.Top and tail the lemongrass and slice thinly, and drop into the chopper.Slice the chillies and also add them to the chopper.
With the back of a knife, lightly bash down on the candlenuts to halve them. Place in the food chopper or mortar, whatever you're using.Process these ingredients to get a rough blend.If using pestle and mortar, pound each ingredient before adding the next one.
Now add the onions, shrimp paste and turmeric and process or pound until you get a fairly fine paste.Tip out most of it into a bowl, leaving about 1 Tbsp in the chopper for the filling.
Prepping the Tamarind
Place the tamarind in a bowl and top with the hot water. Leave to soak while you pick the buah keluak.When ready to use, just strain the tamarind straight into the saucepan using a medium mesh strainer.
Picking the Buah Keluak
Grab a buah keluak and anchor it on a chopping board. With your pestle, pound down on the lip to crack it.Peel out the cracked pieces, then turn it upside down on the board and tap a couple of times to get rid of any loose pieces of shell.The first time you do this, go easy. By the 3rd or 4th seed, you'll get the hang of it and know just how much force to use, so as not to crack the whole shell wide open.
Using the end of a small spoon, a lobster pick or knitting needle, pick out the buah keluak meat and drop it into a bowl.Repeat with the rest of the buah keluak. Be sure to reserve the shells.
Filling the Buah Keluak
Now we make the filling. Place the buah keluak flesh (meat) that you've picked into the chopper/mortar that should have a little spice paste in. Add the prawns, chicken meat, salt, sugar, lime juice and cornflour and process to get a fine, sticky mixture.Tip out into a bowl, or work out of the food chopper/mortar.
Now, using the back of the smallest teaspoon you have, pick the filling and fill your empty shells with it to the brim. Flatten out, set aside. Repeat with all the shells.If you have any of the filling left over, you have 2 choices:1. Add it to the whole dish when we add the buah keluak.2. Freeze it to add to stir fries or for making Nasi Goreng Buah Keluak (coming soon).
Heat the oil in a large saucepan on medium heat and fry the spice paste and lemongrass stalks for 4 minutes, until you get a strong, aromatic smell off it.
Add the chicken, stir to coat the portions with the spice paste. Now add the tamarind and stir.
Tip in the stuffed buah keluak, water, sugar and 6 of the kaffir lime leaves. Hold back on the salt. Bring to a boil.Then reduce the heat down to low, cover, and simmer for 45 minutes to an hour, depending on the size of the chicken portions. Basically, until your chicken is cooked.
At the end of cooking time, taste your ayam buah keluak. Add some salt if necessary, and a little more tamarind, if needed. If you don't like the little bit of bitter, add a tsp of sugar. If it's too dry, add a little water.Drop the last 2 kaffir lime leaves, stir and cook for another minute.Take off the heat, and rest for 10 minutes before serving.