In a dutch oven or soup pot put the olive oil, onion, celery, and carrots, and cook over medium heat for about six minutes.
Add the garlic and cook for one more minute.
Add the yellow split peas or lentils (I like to use the orange lentils), chicken or vegetable broth, tomatoes, potatoes, zucchini, basil, marjoram, oregano, and black pepper. When cooking potatoes I always like to add some salt so that it gets inside the potato, so add about 1/2 teaspoon. Bring the liquid to a boil, reduce heat, partially cover, and cook 45 minutes.
Remove the soup from the heat and let cool about 30 minutes.
Take at least half of the soup and puree it in batches in the food processor (depending on how many chucks of vegetables that you want in your soup).
Return the soup to the stove top. Add 1-2 handfuls of baby spinach and reheat the soup. If the soup is too thick, I like to add some milk to thin it and give it extra nutrition. Check for salt.
When the soup is hot, garnish it with either chopped cilantro or parsley.