From Bon Appetit
1 tbsp olive oil
2 large leeks (white and green parts only) chopped (can substitute 3/4 cup chopped onion)
1 tbsp plu 2 1/2 cups water
2 tsp curry powder
2 small white potatoes, peeled, cut into 1/2 inch pieces
1 tsp salt
4 cups packed fresh spinach
2 cups low fat milk
1/2 cup plain non-fat yogurt
1/4 cup chopped cilantro
Heat oil in large saucepan over medium heat. Add leeks and 1 tbsp water; saute until leeks are tender (about 5 minutes). Add curry powder and stir 30 seconds. Add remaining 2 1/2 cups water, potatoes and salt and bring to boil. Reduce heat, and simmer covered until potatoes are tender (about 10 minutes). Stir in spinach; simmer until just wilted, about 1 minute. Cool slightly.
Working in batches, puree soup in a blender until almost smooth. Return soup to same saucepan. Add milk and bring to simmer. Season with salt and pepper to taste.
Ladle soup into four bowls. Whisk yogurt until smooth. Swirl 2 tbsp yogurt into each bowl. Sprinkle with cilantro and serve.