1. To prepare slaw, with a sharp knife or on a mandoline, shave the cauliflower, cabbage, radicchio, and red onion into very thin slices. Rough chop mint, leaving some larger pieces.
2. To prepare vinaigrette, combine ingredients and whisk until well blended. Toss with vegetables to coat. Adjust salt and pepper to taste. Add satsumas and mint last and lightly toss again to incorporate. Allow flavors to marry for roughly 1 hour, then serve at room temperature.
Optional add-ins: toasted almonds, sunflower seeds, kale