Ingredients
1 onion, chopped
1/4 cup olive oil
2 carrots, diced
2 stalks celery, chopped
4 cloves minced garlic
1 teaspoon dried oregano
2 bay leafves
1 teaspoon dried basil
1 (14.5 ounce) can crushed tomatoes
2 cups dry lentils
8 cups chicken or vegetable broth
1/2 cup spinach, shredded 
1 lb. polish sausage or kielbasa 
2 tablespoons vinegar
salt to taste
ground black pepper to taste

Directions

1. In slow cooker, add all ingredients except for sausage, spinach, and vinegar. Cook on medium for 6 hours.
2. With one hour remaining, add sausage and spinach. 
3. Before serving, stir in vinegar.

Ready in: 6 hours 10 minutes