Begin by preparing the dressing.
Whisk together the fish sauce, lime zest, lime juice, white granulated sugar, minced garlic, and sliced Thai chilis in a small bowl.
Add the water and whisk until the ingredients are well combined.
Set the dressing aside for when you are ready to assemble the salad later.
Wash the lettuce, cabbage, and cucumber, and chop them into bite-sized pieces.
Peel the carrot and slice it into thin, julienned strips.
Set the prepared vegetables aside.
Arrange the lettuce and cabbage on a large serving platter, and then top with the julienned carrot and sliced cucumber.
Sprinkle the chopped cilantro, basil, and mint leaves over the top of the vegetables, and then drizzle the dressing over the salad.
Finally, sprinkle the chopped roasted peanuts and crispy fried onions over the top of the dressed salad.
Serve immediately, garnished with additional fresh herbs, or extra lime juice and fish sauce if desired.