Slow Cooker Curried Lentil Soup

Ingredients

• 2 1/2 cups dried lentils sorted, rinsed
• 8 cups water
• 2 medium carrots cut into 1/2-inch slices
• 2 medium stalks celery cut into 1/2-inch slices (1 cup)
• 1 medium onion chopped
• 2 cloves garlic minced
• 2 extra-large vegetarian vegetable bouillon cubes or 2 chicken-flavor bouillon cubes
• 3 teaspoons curry powder
• 1 teaspoon salt
• 2 bay leaves
• 14 1/2 oz. diced tomatoes undrained
• 2 cups fresh spinach coarsely chopped
• 1/2 cup low-fat plain yogurt