Quarter cabbages and remove tough cores. Discard cores.
Shred both cabbages as finely as possible.
Peel and julienne carrots into thin matchstick strips.
Peel mangoes and cut flesh into thin strips matching the carrot julienne in size.
Combine cabbage, carrots, mango, spring onions, and coriander in a large bowl. Toss gently to distribute.
Whisk all dressing ingredients together until honey is fully dissolved. Taste and balance carefully.
Pour three-quarters of the dressing over the slaw. Toss thoroughly for a full minute.
Add more dressing if needed. Add sliced chilli and toss once more.
Taste and adjust lime, honey, fish sauce, or chilli as needed.
Add peanuts and sesame seeds if using and toss briefly.
Cover and refrigerate for 15 minutes.
Toss thoroughly before serving. Taste one final time.
Transfer to serving bowl. Garnish with coriander, spring onions, chilli, and lime wedges. Serve cold.