Marinate the chicken. In a bowl, combine the chicken pieces with 1 tablespoon fish sauce, the soy sauce, minced ginger, garlic, and black pepper. Mix well and set aside for 15 minutes at room temperature, or up to 2 hours in the fridge.

Make the caramel. Heat the neutral oil in a wide, heavy pan or clay pot over medium heat. Add the sugar in an even layer and let it melt without stirring, swirling the pan once or twice. Cook until it turns a clear amber, about 2 to 3 minutes, then move quickly to the next step before it darkens further.

Add the aromatics. Stir in the sliced shallot and the ginger matchsticks. Cook for about 1 minute, until fragrant and coated in the caramel. Work fast so the caramel does not burn.

Add the chicken. Add the marinated chicken with all of its marinade. Spread the pieces out and let them sit undisturbed for 2 minutes to pick up color, then stir and cook another 2 to 3 minutes, until the edges look opaque.

Braise. Pour in the coconut water (or water), the remaining 1 tablespoon fish sauce, the chilies if using, and the salt. Bring to a lively simmer, then lower the heat to medium-low.

Simmer uncovered for 12 to 15 minutes, stirring now and then, until the chicken is cooked through and tender. The ginger matchsticks should be soft and bend easily.

Reduce to a glaze. Raise the heat to medium and cook 3 to 5 minutes more, stirring often, until the liquid shrinks to a shiny glaze that coats the chicken and pools just a little in the pan. Take care at the end — a reduced caramel can catch quickly.

Rest and serve. Take the pan off the heat and rest 5 minutes. Taste for salt and add a pinch more if needed. Scatter the scallions (and cilantro, if using) over the top and serve over jasmine rice with cucumber on the side.