Shorbat Jarjir Rocket Soup

Name: Shorbat Jarjir (Rocket Soup)
Ingredients: 2 tablespoons light olive oil; 1 medium yellow onion, roughly chopped (about 2 cups); 4 garlic cloves, crushed; 1 teaspoon ground turmeric; 1 teaspoon sea salt; 1/2 teaspoon black pepper; 1/2 teaspoon grated fresh nutmeg; 1/4 teaspoon ground allspice; 1 medium russet potato, chopped; 4 cups homemade or low-sodium chicken or vegetable stock; 7 ounces arugula; 5 1/4 ounces fresh spinach; 1 ounce cilantro sprigs (about 1/2 packed cup); Plain whole-milk Greek yogurt, for serving; 2 tablespoons extra-virgin olive oil