Drain the yogurt on a fine sieve or in a fine cloth over a suitable bowl for 4-5 hours.
Peel the cucumber, remove the seeds and grate. Place the grated cucumber in a large salad bowl. Peel off the garlic cloves, mash them with salt and pour in the olive oil while stirring. Add the finely chopped dill. Pour this mixture into the salad bowl.
Put the drained yogurt in the salad bowl and stir well. Salt to taste. Sprinkle with dill and the grated walnuts and serve.
Alternative: arrange in portions and serve with the walnuts sprinkled with it.