On a cutting board, trim any fat off the chicken and then slice the chicken across the grain into 1/4-1/2-inch slices.
In a large bowl, combine 1 1/4 water and 1 Tbsp baking soda, add the chicken to the bowl and then toss, let the chicken stand at room temperature in the water mixture for 15 minutes.
Rinse the chicken in a sink colander and then let it rest to drain well.
In a medium saucepan, combine 3 Tbsp water and sugar and whisk, then bring to a boil over medium-high heat and let cook without stirring for 4-6 minutes. It should become a golden-brown color.
Reduce the heat to medium-low and continue to cook, swirling the saucepan gently, until the sugar turns the color of molasses, and the temperature reaches 390-400 degrees Fahrenheit.
Immediately remove the saucepan from the heat and carefully pour in 3/4 cup hot water being careful because the mixture will steam and bubble, once the bubbling stops, return the saucepan to the burner at medium-high heat and continue to stir until the sugar is dissolved.
Transfer the caramel to a 12-inch skillet and then stir in the fish sauce and ginger.
Add the rinsed chicken to the caramel sauce and simmer over medium-high heat, then reduce the heat to medium-low, cover the saucepan and simmer the chicken in the caramel sauce until the chicken temps at 205 degrees.
Flip the chicken after simmering for 15 minutes, then simmer another 15-20 minutes.
Transfer the chicken to a serving dish and then cover to keep warm.
Bring the sauce in the saucepan back to a boil and cook until it reduces to 1 1/4 cups which should take 3-5 minutes.
Whisk the cornstarch with 1 Tbsp water in a small bowl, then whisk it into the caramel sauce and simmer until thickened.
Stir in pepper and mix well.
Pour 1/4 cup sauce over the chicken and then sprinkle with cilantro if using.
Finally, serve with remaining sauce and enjoy!
Keyword Dinner under $25, Recipe, Vietnamese Caramel Fish