Set the oven to 190 C. You will need an ovenproof pot to bake your chicken in.
Put the onion, garlic, ginger, turmeric, chilli paste, sugar, soy sauce, lime zest and tomato puree into put a food processor and pulse into a paste. (You could also use a stick blender for this. Just make a nice smooth paste. This will form your sauce)
Pour the paste into a bowl and add the 6 pieces of chicken turning to coat in the marinade while you get the other ingredients ready.
Heat the pot you will use to bake the chicken. Add the oil and then shake off excess marinade from each piece of chicken and add one by one to the pot. Sear on both sides till golden and coloured. Take out of the pot and set aside once done. Remember this is just to seal and colour the outside
Add the flavour paste to the pot and stir while it is cooking. The paste needs to cook out. (Cooking the paste cooks out the water and then caramelises and sweetens it.) This will take about 5- 8 minutes on a medium to high heat. It will begin to darken and smell fragrant. Add the sweet soy sauce and stir in well for 1 minutes. Don't let the paste catch on the bottom. Reduce the heat if you need to.
Pour in the coconut, lime juice then add the lemon grass, lime leaves and a small pinch of salt. Stir well.
Return the chicken to the pot letting it peak above the sauce to further brown and colour and bake without a lid for around 40 minutes. Test one of the thighs by piecing with a knife. The juices should run clear.
Serve with rice. You can also add chopped roasted macadamia nuts or peanuts and crispy fried shallots ( from Asian supermarkets)