Chilled Persian Yogurt Soup

• 1/2 cup walnuts
• 1/4 cup dried rose petals, crushed
• 2 cup greek yogurt
• 1 1/2 cup ice water
• 1/2 cup golden raisins
• 1/2 seedless cucumber, peeled and finely diced
• 1/4 cup mint, finely chopped
• 1/4 cup dill, finely chopped
• 1/4 cup chives, finely chopped
• salt
• freshly ground black pepper
• ground sumac, for garnish

1. Preheat the oven to 350 degrees F. Spread the walnuts on a baking sheet and toast for about 10 minutes. Let cool, then chop finely.
2. In a small bowl, cover the rose petals with cold water and let stand until softened, about 20 minutes. Drain the petals and squeeze dry.
3. In a large bowl, whisk the yogurt with the ice water. Stir in the raisins, cucumber, mint, dill, chives, walnuts, and rose petals. Season with salt and pepper. Refrigerate for at least 1 hour, until very cold. Serve the soup sprinkled with sumac.