For the prune purée: In food processor, process 1⅓ cups dried plums and 6 tablespoons hot water until puréed.
Recipe created by Leslie Bonci, MPH, RD, CSSD, LDN for the California Dried Plum Board.
Combine the cauliflower, dried plums, green onions, and red peppers in a bowl.
In a separate bowl, mix the vinegar, olive oil, dried plum purée, celery seed, tarragon, and some salt and pepper. Pour over the vegetables. Mix well. Let marinate for about 1 hour before serving.