Wash the pumpkin thoroughly, remove the seeds, and cut into bite-sized pieces.
Place the pumpkin pieces in a steamer and steam for about 15 minutes.
Peel the steamed pumpkin and mash it.
Finely chop onion, cucumber, and apple.
Add mayonnaise, salt, and pepper to the mashed pumpkin and mix well.
Add the chopped ingredients and mix evenly.
Transfer to a plate and serve.