Peel the potatoes and cut them into bite-sized pieces.
Peel the sweet potatoes and cut them into bite-sized pieces.
Place the potatoes and sweet potatoes in a steamer and steam for 15 minutes.
Put the cooked potatoes and sweet potatoes in a bowl and mash them.
Season with salt and pepper.
Add plain yogurt and chopped cucumber, then mix well.
Chill in the refrigerator for 10 minutes and serve in a dish.