Cut the little red radishes into thin slices, the apple into bite-sized wedges and the cheese into short sticks. Combine the ingredients in a medium salad bowl.
In a separate bowl mix the yogurt, mustard, lemon juice, salt, pepper and sugar until the ingredients come together as a smooth dressing. Pour over the salad.
Chill for about half an hour to let the ingredients combine well. Garnish with your favorite sprouts and serve.