Slice the green and purple cabbage into very thin strips using a sharp knife or mandoline slicer. You should have about 2 cups of each. This takes about 5 minutes. Checkpoint: Cabbage should be thin enough to see light through individual slices.

Julienne (cut into thin matchsticks) the 3 carrots using a julienne peeler or knife. This takes about 3–4 minutes. If you don't have a julienne peeler, a box grater works fine. Checkpoint: You should have about 1.5 cups of carrot matchsticks.

Slice the red bell pepper into very thin strips, removing seeds and white pith first. Slice the green onions into thin rounds, separating white and green parts. This takes about 3 minutes. Checkpoint: Vegetables should be uniform in size for even texture.

Place a dry skillet over medium heat for 30 seconds until warm. Add 3 tablespoons sesame seeds and toast, stirring constantly, for 1–2 minutes until light golden and fragrant. Immediately transfer to a small plate. Do not let them burn. Checkpoint: Sesame seeds should smell nutty and toasted, not burned or bitter.

In a small mixing bowl, add 3 tablespoons rice vinegar, 2 tablespoons soy sauce, 1 tablespoon sesame oil, 1 tablespoon honey, 1 teaspoon fresh ginger (grated), 2 cloves garlic (minced), 1 teaspoon lime juice, and 1/2 teaspoon red pepper flakes. Whisk together for 30 seconds until combined. Checkpoint: Dressing should smell aromatic with balanced sweet and savory notes.

While whisking continuously, slowly drizzle in 2 tablespoons vegetable oil into the dressing bowl. Whisk for about 1 minute until the oil is fully incorporated and the dressing looks slightly thickened. Checkpoint: Dressing should be smooth and slightly emulsified, not separated.

In a large mixing bowl, combine the sliced green cabbage, purple cabbage, carrots, red bell pepper, green onions, and 1/4 cup fresh cilantro (chopped). Do not add dressing yet. Checkpoint: All vegetables should be prepped and ready to dress.

Pour the entire dressing over the vegetables and toss vigorously using two forks or tongs for 2–3 minutes until all vegetables are evenly coated and slightly wilted. Checkpoint: Every piece of vegetable should glisten with dressing; no dry spots should remain.

Sprinkle the toasted sesame seeds over the top and toss gently one more time to distribute. This takes 30 seconds. Checkpoint: Sesame seeds should be visible throughout.

Taste a bite of the slaw. The flavor should be balanced: slightly tangy, savory, with a hint of heat and sweetness. If it needs more lime juice, add a squeeze. If it needs more soy sauce, add 1/2 teaspoon at a time. This takes 1 minute.

Serve immediately for maximum crispness, or cover and refrigerate for up to 2 hours. If chilling, stir again just before serving to redistribute the dressing.