Prepare the Vegetables: Thinly slice the green and red cabbage. Julienne or shred the carrots. Thinly slice the red bell pepper. Chop the fresh cilantro and green onions. If using peanuts, give them a rough chop.
Make the Dressing: In a small bowl, whisk together the rice vinegar, soy sauce, sesame oil, honey (or maple syrup), grated ginger, minced garlic, and red pepper flakes (if using). Continue whisking until well combined and the honey is dissolved.
Combine the Slaw: In a large mixing bowl, combine the sliced cabbages, julienned carrots, sliced red bell pepper, chopped cilantro, and chopped green onions. Toss gently to distribute the ingredients evenly.
Dress and Toss: Pour the prepared dressing over the vegetable mixture. Toss everything together thoroughly until all the ingredients are coated with the dressing. If using peanuts, add them now and toss gently one last time.
Rest and Serve: For best flavor, let the slaw sit for at least 10-15 minutes before serving to allow the flavors to meld and the vegetables to slightly soften. This step is crucial for a truly delicious slaw.