Let the slow cooker work all day with a simple step at the end for a quick and delicious dinner, or cook overnight to fill those wide-mouth vacuum insulated bottles for lunch.
Wash and pick over 1 cup lentils, removing any stones or moldy lentils. Place in slow cooker insert.
Peel and mince 4 cloves garlic. Peel and dice 2 onions. Wash, peel (optional), and dice 1 1/2 lbs. potatoes or turnips (if mature, peel the turnip skin). Place vegetables in slow cooker insert.
Add 8 cups water, 1 TB fennel seed, 1 TB dried oregano, 1 tsp. dried thyme, and 1/2 tsp. coarsely ground black pepper.
Cover and cook on low 8-10 hours.
Add 2 tsp.-1 TB salt.
Wash and chop into bite-size pieces 1/2-3/4 lb. spinach or chard.
In a large frying pan over high heat, warm 1 TB olive oil. When the oil ripples, tilt pan to coat with oil and add spinach. Sauté 1-2 minutes until spinach wilts. Stir into soup with 1/2-1 TB balsamic vinegar. Adjust seasonings to taste.