Lentil Soup

1 onion, chopped
1/4 cup olive oil
2 carrots, diced
2 stalks celery, chopped
2 cloves garlic, minced
1 teaspoon dried oregano
1 bay leaf
1 teaspoon dried basil
1 (14.5 ounce) can crushed tomatoes
2 cups dry lentils
8 cups water
1/2 cup spinach, rinsed and thinly sliced
2 tablespoons vinegar
salt to taste
ground black pepper to taste
Directions

In a large soup pot, heat oil over medium heat. Add onions, carrots, and celery; cook and stir until onion is tender. Stir in garlic, bay leaf, oregano, and basil; cook for 2 minutes.
Stir in lentils, and add water and tomatoes. Bring to a boil. Reduce heat, and simmer for at least 1 hour. When ready to serve stir in spinach, and cook until it wilts. Stir in vinegar, and season to taste with salt and pepper, and more vinegar if desired.