Remove the backbone from the chicken using kitchen shears. Place the ginger, garlic, chilies, coriander, turmeric, lemongrass, salt, lime zest, lime juice, brown sugar, cayenne and grapeseed oil into a food processor or blender. Process to a fine paste. Rub this mixture all over the chicken , and kaffir lime leaves and place in the refrigerator for 8–12 hours or overnight.
Remove from the oven 1 hour before roasting. Place in a baking pan. Add kaffir lime leaves (if using). Melt the coconut oil and pour over the chicken. Preheat oven to 425°. Bake for 20 minutes and then drop the temperature to 375° for another 35–40 minutes. The flattened chicken will cook quicker than a regular roasted chicken. Remove from the oven when the juices run clear. Serve with rice and sambal.
To make the sambal: Place all of the ingredients in a food processor and process
until finely chopped.