Random Vegetable Soup

I just bought a few dollars worth of vegetables from the slightly blemished section of the produce stand and decided to make soup with it. I don't think this recipe works well as something to actually follow, but instead as an example of how one can make soup with pretty much any assortment of vegetables, if they're all cooked in batches to that they get done at around the same time. And the nice thing about this method is that you always get a soup where all the ingredients really taste just like themselves.

Ingredients:
1 yellow onion, chopped large
1 head garlic, top 1/4th cut off
1 T oil
1 sweet potato, diced medium
6 baby red potatoes, diced medium
1 white potato, diced medium
1/2 bu celery, peeled and sliced 1/4" thick
4 carrots, peeled and sliced 1/4" thick
2 bu thin asparagus, bottom 1/3 cut off
2 tomatillos, diced small
1 zucchini, diced small
1 t oil
salt & pepper to taste
1-2 T white wine vinegar, to taste

Instructions:
1. Preheat oven to 425 degrees.
2. Toss the garlic and onion with the oil and roast in the oven 25 minutes.
3. Start a large pot with 2 qts water simmering over medium-low heat. Add all the vegetable scraps to it and start to simmer.
4. When the garlic and onions are done roasting, squeeze the garlic cloves out of the head and add them to the stock along with the roasted onions. Simmer the stock for around 45 minutes total, then strain.
5. Put the stock in a pot and add the sweet potato, potatoes, carrots and celery. Cook for 20 minutes over medium-low heat. Top the pot off with water if the level is too low.
6. Get a sauté pan very hot and add a teaspoon of oil. Sauté the asparagus, tomatillo and zucchini until slightly browned.
7. Season the soup to taste with salt, pepper and vinegar, and serve garnished with the green vegetable sauté.