Red Lentil and Vegetable Soup with Chive Yogurt

Name: Red Lentil and Vegetable Soup with Chive Yogurt
Ingredients: 1 tablespoon extra-virgin olive oil; 1/2 cup finely chopped red onion; 3 garlic cloves, minced; 2 tablespoons finely minced peeled ginger; 8 cups low-salt chicken broth or water; 1 russet potato, cut into 1/2-inch pieces; 2 cups red lentils, rinsed well; 2 carrots, peeled, cut into 1/2-inch pieces; 2 cups (packed) spinach leaves; Kosher salt and freshly ground black pepper; 1/2 cup nonfat Greek-style yogurt; 1 tablespoon finely chopped fresh chives