Here's my lentil soup. It's very basic, easy to prepare, and absolutely delicious.
Lentil Soup
2 tbsp olive oil
1 med onion, chopped
1 carrot, diced
1 stalk celery, chopped
2 cloves garlic, chopped
1 tsp dried oregano
1 bay leaf
1/2 tsp dried basil
1 reg. sized can (16oz?) tomatoes (chopped, stewed or crushed)
8 cups liquid (chicken broth, water or a mixture of both)
1 lb (2 cups) dried lentils
1 or 2 potatoes, diced (optional)
1/2 cup fresh spinach, sliced (optional)
2 tbsp vinegar, or to taste
Salt and pepper to taste
Saute onions, carrots and celery in olive oil until tender. Add all other ingredients except the spinach, vinegar, salt and pepper. I don't usually use potatoes in mine but many people prefer to add them. Simmer until the lentils are tender, approximately 1 hour. Season to taste with salt, pepper and vinegar. Don't omit the vinegar - it's important. I use white vinegar, but cider, wine or balsamic can be substituted. Add spinach, if desired, and cook until it wilts. When I use spinach, I remove it from any leftovers and add fresh when I reheat it. I don't like the texture when the spinach has been refrigerated or frozen.