Add the lemongrass, cilantro (coriander), shallots, and garlic to a mortar and pestle, and pound until pulverized. You can also use a food processor for this step.
Add the oil, sugar, salt, black pepper, Thai soy sauces, fish sauce and turmeric (if using). Mix until well-combined.
You can butterfly or spatchcock your chicken for grilling like it’s done on the streets of Thailand. However, I cut the chicken into individual pieces to ensure they’d cook properly. This way, I can pull each piece off the grill once cooked. Rub the chicken with the marinade paste, ensuring every piece is thoroughly coated. Cover and place in the refrigerator to marinate overnight (or at least 12 hours).
The next day, take the chicken out 1 to 2 hours before you’re ready to grill.
Make the sauce:
In a small bowl, mix the sugar and hot water until the sugar is dissolved. Mix in the rest of the sauce ingredients and set aside.
Cook the chicken:
Place the chicken on the grill, and use any remaining marinade to baste the chicken while grilling. Leave the marinade paste on the chicken, including any chunks of herbs as they will caramelize and add flavor. Turn and baste the chicken often to create a nice flavorful outer crust. Baste the chicken with the leftover marinade in the first half of the grilling process, but do not do this towards the end of cooking. The raw chicken marinade needs enough time to fully cook.
Serve immediately with some coconut rice, your nam jim jeaw sauce, and lime wedges!