Wash the chestnut pumpkin thoroughly, peel, and cut into bite-sized pieces.
Steam the chestnut pumpkin for about 15 minutes until tender.
Cool the steamed chestnut pumpkin, place it in a bowl, and mash with a fork.
Add mayonnaise, plain yogurt, salt, and pepper, and mix well.
Add chopped nuts, dried cranberries, and chopped cucumber or apple, and mix gently.
Transfer the finished salad to a bowl, refrigerate, and serve chilled.