Sort and wash the lentils. Combine lentils, water, and next 6 ingredients (water through bay leaves) in a large Dutch oven; bring to a boil. Cover, reduce heat, and simmer 45 minutes or until tender.
Melt butter in a large nonstick skillet over medium-high heat. Add the onion and cumin; sauté 10 minutes or until browned. Stir onion mixture into lentil mixture. Discard bay leaves and parsley. Add chard to soup; simmer, uncovered, 10 minutes or until chard is tender. Remove soup from heat. Stir in juice and pepper. Ladle 1 1/3 cups soup into each of 6 bowls; top each serving with 1 tablespoon yogurt. Yield: 6 servings.