Put Romaine hearts and radicchio in a bowl of ice water, soak for 20 minutes, and drain. Add more fresh water and soak for an additional 20 minutes (this removes bitterness). Drain, dry and set aside.
For the dressing:
Place the fennel seeds in a small saute pan over low heat. Toast, tossing occasionally, about 2 to 3 minutes, or until lightly browned. Crush the toasted seeds in a mortar and pestle or seal in a plastic bag and roll with a rolling pin.
In a saucepan, place the honey, champagne vinegar and toasted fennel seeds. Bring to a boil, stirring well. Remove from heat. Whisk in olive oil and season with salt and pepper.
Place the radicchio, cabbage and watercress into a bowl. Add dressing while warm and toss well. Serve immediately.