In a medium bowl, combine the minced lemongrass, garlic, fish sauce, brown sugar or honey, soy sauce, vegetable oil, turmeric (if using), black pepper, and water to create the marinade. Mix well until the sugar dissolves.
Place the chicken pieces into a resealable bag or a non-reactive dish. Pour the marinade over the chicken, ensuring all pieces are coated.
Refrigerate and marinate the chicken for at least 4 hours, or preferably overnight for the best flavor.
Preheat your grill (charcoal or gas) to medium-high heat (about 400°F or 200°C). Lightly oil the grates.
Remove the chicken from the marinade, letting excess drip off. Discard the remaining marinade.
Grill the chicken for 5 to 7 minutes per side, depending on thickness, until cooked through and slightly charred on the edges. If using thighs, they may take slightly longer.
If the chicken looks dry, you can lightly brush it with a small amount of reserved oil during the last few minutes of cooking.
Remove the chicken from the grill and let it rest for 5 minutes before serving.
Notes
For skewers, thread the marinated chicken pieces onto metal or soaked wooden skewers before grilling.
This chicken is excellent served over broken rice (Cơm Tấm) or with vermicelli noodles (Bún).
For Bánh Mì sandwiches, slice the grilled chicken thinly after resting.