Step 1

Add the lemongrass, coriander roots, garlic, and shallots to a mortar and pestle and pound into a fine paste. Next, add the chilies and pound until the paste is smooth. Stir in the light soy sauce, fish sauce, sweet dark soy sauce, ground white pepper, freshly cracked black pepper, turmeric powder, kosher salt, and coconut sugar until combined well. (Note: Alternatively, you can bend all the marinade ingredients into a smooth paste using a blender. You will need to uncover and scrape the sides of the blender jug.)

Step 2

Place the chicken breast side down with the legs facing you on a chopping board. Using kitchen scissors, cut through both sides of the backbone and remove it. (Freeze it in a sealed freezer-friendly bag to make chicken stock another time, or discard it.) Use some paper towels to wipe out and slimy or bloody bits on the inside. Then turn the chicken over and press down on the breastbone to flatten the chicken. (You may hear a crack).

Step 3

Place the chicken in a large mixing bowl and pour the marinade all over the chicken. Using your hands (wear disposable gloves if needed), rub the chicken all over with the marinade. Loosen the skin over the breasts and rub the marinade under the skin on the flesh. Turn the chicken around and do the same on the bottom side. Then place the chicken breast side down in the bowl and cover with cling wrap. Allow to marinate for 3 hours in the fridge, or overnight for best flavor. (Remove the chicken from the fridge 30-40 minutes before you’re ready to roast to take the chill off.)

Step 4

Preheat oven to 190°C/374°F. Line a baking tray with aluminum foil and place a baking rack on top. Place the chicken skin side up on the rack and tuck the wing tips underneath. Spoon some of the marinade evenly on top. Pour 2 cups of water into the baking tray (this will prevent any dripping marinade from becoming too smoky and burning). Place the chicken into the oven and roast for 25 minutes. Meanwhile, transfer the remaining marinade into a small saucepan or pot. Simmer over medium heat for 2-3 minutes or until slightly thickened. Remove the chicken from the oven and baste with thickened marinade. Place the chicken back in the oven and roast for 15-20 minutes more, until the chicken has cooked through. (The chicken is cooked through when a digital thermometer inserted in the inner thigh area near the breast but not touching the bone registers 73°C/165°F. If you don’t have a digital kitchen thermometer, you can check if the chicken is done by cutting into the area between the leg and breast – the juices should run clear. If the juices are pink, place the chicken back in the oven for a few more minutes to finish cooking.) Transfer the tray to a cooling rack and allow the chicken to rest for 10-15 minutes.

Step 5

Place the whole chicken on a large serving plate or platter and carve at the table. Or cut into piece and arrange on the platter. Garnish with coriander and serve with the Nam Jim Jaew, cucumber slices, and warm steamed rice.

Step 6

While the chicken is roasting (or resting after cooking), prepare the spicy dipping sauce. Toast the glutinous rice in a dry skillet until golden brown and it smells like popcorn. Transfer to a mortar and pestle and pound into a fine powder (or use a spice grinder to grind). Then transfer to a small bowl and add the tamarind paste, fish sauce, lime juice, coconut sugar, and Thai chili powder. Mix with a spoon to combine, then stir in the garlic, shallot, and coriander. Taste and adjust sugar and lime juice if needed. Then set aside until ready to serve.