Curried Fresh Asparagus Soup

1 tablespoon extra virgin olive oil
1 medium onion, chopped
1/2 teaspoon salt
1 teaspoon curry powder
1/4 teaspoon ground ginger
zest and juice of 1 lemon, divided
2 cups diced and peeled red potatoes
3 cups vegetable or chicken broth
1 cup coconut milk
1 bunch asparagus, trimmed and cut into 1/2-inch pieces
Fresh ground pepper to taste
1/4 cup Crème fraîche or sour cream
1/4 cup finely chopped green onions or chives

1. Heat oil in a large soup pot over medium heat. Add onion and salt and cook, stirring often, until golden brown, about 5 minutes. Stir in curry, ginger, lemon zest, and potatoes and cook, stirring occasionally for about 5 minutes.
2. Stir in the broth, coconut milk and asparagus. Bring to a simmer over medium heat, partially cover and continue to cook until potatoes are tender, about 15 minutes. Puree the soup with an immersion blender until smooth.
   
3. Whisk Crème fraîche or sour cream, lemon juice, and green onions or chives in a small bowl. Divide the soup into 4 bowls and garnish with the cream mixture.