Cut one cucumber half in thin (about 0.5cm/0.2″) lengthwise slices. Divide the slices in two cucumber halves and place them both cut side on the chopping board. Slice them again, so that you have long, thin ‘sticks’. Hold them together with one hand, while you chop the cucumber widthwise, as you normally would. Now you have very fine cubes. Repeat this with the other half.
Crush or chop the walnuts until the pieces are fairly small.
If you want to use garlic, finely chop the cloves or press them through a garlic press.
Combine all the ingredients with the creamy yoghurt and season with salt to your liking.
If you like, you can garnish the Mast o Khiaar with crushed or whole little rose petals. Serve as an appetiser with crackers, bread or crisps or as a side with rice and Persian stews.