1 bunch scallions, chopped
1 3-inch piece ginger, peeled and roughly chopped
1/2 jalapeno pepper (remove seeds for less heat)
2 tablespoons packed light or dark brown sugar
1 tablespoon fish sauce
1 tablespoon soy sauce
1 tablespoon rice vinegar (not seasoned)
1 plum tomato, halved
6 skinless, boneless chicken thighs (about 21/4 pounds), quartered
4 ounces shiitake mushrooms, stemmed and quartered
2 bunches watercress, tough stems removed
White rice, for serving
Put all but 2 tablespoons of the scallions in a blender; add the ginger, jalapeno, brown sugar, fish sauce, soy sauce, vinegar, tomato and 1/4 teaspoon salt and blend until smooth. Transfer to a 6-quart slow cooker.
Add the chicken and mushrooms to the slow cooker and stir to coat. Cover and cook on low, 4 hours.
Roughly chop the watercress and stir into the slow cooker. Serve the chicken and vegetables with rice; top with the reserved scallions.