2 teaspoons Dijon mustard
2 prunes, soaked until soft, or overnight
2 teaspoons red wine vinegar
2 tablespoons shredded carrots
2 tablespoons shredded cucumber
1/4 cup chopped red onion
1/4 cup chopped green or red bell pepper
1/2 ripe avocado, peeled and pitted, cut into 4 slices
4 tomato slices
2 large collard leaves, thick stem removed (see note)
2 medium romaine leaves