In a large saucepan melt butter. Add vegetables, garlic and bay leaf, sauté until vegetables are tender. Add lentils, chicken stock, tomato, pepper, and cumin to vegetable mixture. Pour enough water into saucepan to cover. Simmer until lentils are tender, approximately 30 minutes.
Add spinach (or kale) and salt, and cook on low for 5-10 minutes, until spinach has wilted.
Optional: Pour hot soup into a blender and puree.
Serve immediately and garnish with cheddar cheese.
Promptly store leftovers in an airtight container in the refrigerator, for up to 4 days.Nutritional values are approximate and based on 1/4 the recipe. Does not include cheese garnish.