• 3 tablespoons extra-virgin olive oil
• 1 small onion , diced into 1/4-inch pieces
• 2 carrots , peeled and diced into 1/4-inch pieces
• 2 stalks celery , diced into 1/4-inch pieces
• 3 cloves garlic , finely chopped
• 2 tablespoons peeled, grated fresh ginger
• 1 tablespoon curry powder
• 1 teaspoon ground cumin seeds
• 1 teaspoon ground coriander
• 1 lemon , juiced (about 1/4 cup)
• 2 large limes , juiced (about 1/2 cup)
• 1/2 grapefruit , juiced (1/3 cup)
• 1 bay leaf
• 10 cups chicken or vegetable stock
• 1 cup (1/2 pound) lentils , rinsed and picked through
• 1/2 cup chopped cilantro
• Salt and freshly ground pepper
• Plain yogurt or sour cream , for garnish

In a 5-quart Dutch oven or soup pot, heat olive oil over a medium flame. Add onions, carrots, and celery. Cook until tender and slightly browned, about 10 minutes. Add garlic, ginger, curry, cumin, and coriander; stir 30 seconds. Add lemon, lime, and grapefruit juices; bay leaf; stock; and lentils. Raise heat to high, bring to a boil, and reduce heat to medium-low, allowing lentils to simmer. Continue simmering 45 to 55 minutes, until lentils are tender.

Remove bay leaf, add cilantro, and season to taste with salt and pepper. (Depending on stock used, soup may need up to one tablespoon salt.) Serve hot with a dollop of yogurt or sour cream.