Lentil and Vegetable Soup with Chive Yogurt

• 1 Tbsp extra-virgin olive oil
• 1/2 cup finely chopped red onion
• 3 garlic cloves, minced
• 2 Tbsp finely minced peeled ginger
• 8 cups chicken or vegetable broth or water
• 1 large white or sweet potato, cut into 1/2-inch pieces
• 2 cups lentils, rinsed well
• 2 carrots, peeled, cut into 1/2-inch pieces
• 2 cups (packed) spinach leaves or slivered chard or kale
• Kosher salt and freshly ground black pepper
• 1/2 cup nonfat Greek-style yogurt
• 1 Tbsp finely chopped fresh chives or scallions

Heat oil in a small pot over medium heat. Add onion and cook, stirring occasionally, until soft and light golden, about 5 minutes. Stir in garlic and ginger and cook, stirring constantly, for 1 minute. Add broth, potato, lentils, and carrots; bring to a simmer and cook, partially covered and stirring occasionally, until lentils and vegetables are tender, about 15 minutes. Stir in spinach (or greens) and season to taste with salt and pepper. Meanwhile, stir yogurt and chives in a small bowl; season to taste with salt and pepper. Ladle soup into bowls and serve with a dollop of chive yogurt.