Hard boil eggs, cool under cold water, peel and cut.
Use a paring knife to remove tough fibers from the outside of the rhubarb stem. Cut the stalk across the thinnest slices, salt.
Separate all the inflorescences from the head of cauliflower (the stems can not be thrown away, but used later for soup or stew). Finely chop the parsley.
For dressing: Combine parsley, mayonnaise, yogurt, lemon juice and olive oil, salt and pepper.
Mix rhubarb, egg and cauliflower, pour over the dressing, mix, let it brew for 15 minutes. and serve.