This is a very basic soup, but somehow it tastes so good. The recipe allows for a lot of variation, which comes in handy. I used prosciutto, potatoes, zucchini, and spinach for my optional ingredients. I used vegetable broth made from Better than Bouillon Vegetable Base. It's a pasty bouillon that is kept in the fridge (I use the chicken base as well). I know making homemade broth is so much better, but in a pinch I use this stuff. Also, the Parmesan cheese isn't just for garnish--it really makes a big difference, so don't skip it!
from How to Cook Everything by Mark Bittman
1/4 cup extra virgin olive oil
1 medium onion, diced
1 carrot, diced
1 celery stalk, peeled and diced
1/2 cup chopped prosciutto or other ham (optional)
1 1/2 to 2 cups hard vegetables, like potatoes, winter squash, parsnips, or turnips, peeled if necessary and cut into smaller than 1/2-inch dice
salt and freshly ground black pepper
6 cups chicken, beef, or vegetable stock or water
1 cup peeled, seeded, and chopped tomato (canned is fine; include the juices)
1 1/2 to 2 cups soft vegetables, like green beans, cooked dried beans, zucchini or summer squash, or dark, leafy greens like kale or collards, cut into smaller than 1/2-inch dice
1/2 cup chopped fresh parsley leaves
freshly grated Parmesan cheese for garnish
1. Put 3 tablespoons of the oil into a large, deep pot over medium heat. When hot, add the onion, carrot, and celery. Cook, stirring, until the onion softens, about 5 minutes. Add the ham if you're using it and cook, stirring, for another 3 minutes.
2. Add the hard vegetables and sprinkle with salt and pepper. Cook, stirring, for a minute or two, then add the stock and the tomato; bring to a boil, then lower the heat so the mixture bubbles gently. Cook, stirring every now and then, until the vegetables are fairly soft and the tomato is broken up, about 15 minutes.
3. Add the soft vegetables and the parsley and adjust the heat once again so the mixture simmers. Cook until all the vegetables are very tender, about 15 minutes. Taste and adjust the seasoning, add the remaining tablespoon of olive oil, and serve, passing the cheese at the table.