In a small skillet, cook walnuts in 2 tablespoons oil over medium heat for 1 minute. Stir in the sugar, honey, allspice, cinnamon and cloves. Cook 3-4 minutes longer or until sugar is melted and nuts are evenly coated. Cool on waxed paper.
In a large bowl, combine the cabbage, caulifloweretes, watercress, radicchio, cranberries and red onion. In a small bowl, whisk the pomegranate juice, vinegar, mayonnaise, garlic, salt, red pepper flakes and remaining oil. Stir in mint if desired. Pour over cabbage mixture; toss to coat.