Place everything in a slow cooker except cilantro, spinach and lemon juice
2 cups red lentils, 7 cups vegetable broth, 2 celery stalks, 2 carrots, 2 medium potatoes, ½ red onion, 3 cloves garlic, 3 tablespoons curry powder, 1 teaspoon ginger powder, 2 small bay leaves, 2 tablespoons soy sauce - or Tamari if gluten free, 14 oz diced tomatoes, salt and pepper to taste if needed