1 large or 2 small shallots, peeled, halved lengthwise and thinly sliced
6 garlic cloves, minced
1-inch fresh ginger, peeled and minced
1/2 teaspoon red chile flakes, or to taste
1/4 teaspoon black pepper
Instructions
Combine the fish sauce, soy sauce, and ¼ cup water in a measuring cup or any container that you can easily pour from. Set aside.
Put the sugar in a heavy-bottomed saucepan. Add ¼ cup water and stir to combine. Cook over medium heat, gently shaking the pan occasionally, but not stirring with a spoon or any other utensil. Once the sugar melts and begins to bubble, continue cooking, shaking the pan occasionally, until the caramel darkens to the color of iced tea, 5 to 7 minutes.
While the caramel cooks, prepare the lemongrass. Cut off the woody tops as well as the hard base at the root end. Peel off any tough outer layers and discard. (A good rule of thumb is that if you have a hard time getting your knife through it, you’ll have a hard time chewing it.) Depending on the size of the original stalks, you’ll be left with about 4 to 6 inches of usable lemongrass from each one. Slice the stalks in half lengthwise, then crosswise as thinly as you can; you should wind up with about ½ cup, but a little less or more is perfectly fine.
When the caramel has darkened to the color of iced tea, remove it from the heat (I like to set the saucepan in the sink to be super careful). Carefully pour in the fish sauce mixture; it will bubble up vigorously, so stand away from the pan. Return the pan to medium heat and cook, stirring constantly, until the caramel melts into the liquid, a minute or 2.
Add the remaining ingredients, cook for another minute, and turn off the heat. Let the caramel cool completely, and store it in a sealed container in the fridge for up to two weeks.