Prepare the dressing by mixing together the mustard, vinegar, oil, apple and half the onion. Divide the squash flower into two and pick the small flowers off the peppermint. The other flowers can be left whole.
Wash, dry and tear up the salad leaves and place them in a bowl or on a dish that is large enough to accommodate all the ingredients. Finely chop the spring onion.
Boil the duck eggs for 8 minutes, cool, peel and divide into boats.
Boil some water in a small saucepan. Shell the broad beans: open the pod, pick out the beans, tear a small hole in the skin that surrounds each bean and carefully remove the green core. Boil the beans for 45 seconds. Sieve and cool. Cook the sugar snap peas in the same way, although these can remain whole.
Split the duck hearts lengthwise, season with salt and pepper and sauté in a hot pan until they acquire a golden brown crust.
Mix together the salad, beans, peas, spring onion and dressing. Turn well so that everything is covered. Arrange the flowers, duck eggs and duck hearts on the top.