Sometimes I write recipes down, sometimes I just use what's in the kitchen.
Here's my soup as best as I can remember how I made it (I made it several weeks ago and froze some). It came out wonderfully good. Sorry, but the amounts are approximate:

Wash and cut maybe 5 red skinned new potatoes into chunks (leave skin on) and put in a pot with about 4 inches to simmer until mostly tender. The potatoes are about 3" in diameter.
Cut a whole large onion into about 1" pieces, a clove or two of garlic, and brown in a skillet with a bit of olive oil. This browning really adds flavor, so don't skip it.
After onion starts browning in the skillet, add one or two handfuls of sliced oyster mushrooms, keeping heat high for a minute and stir fry all briefly. Add maybe 2-3 large leaves (with stems) of bok choy which you have cut up, stir fry for about one more minute, then remove the skillet from heat and set aside. Cut up a tomato and let it drain to one side.

After potatoes are 'mostly' cooked but not mushy, drain them and put in a large soup pot with about 6 cups fresh water. Use a potato masher to mash them up a bit- it's ok for it to still be somewhat chunky. Bring to a simmer and add salt and black pepper to taste. Once simmering, add the skillet ingredients and the tomato and turn heat to LOW. Cover and let cook on low for about an hour. You want it to be just barely simmering.
When you are ready to eat, remove soup from heat and stir in about a cup of 1/2 & 1/2 and maybe a pat or two of butter. Don't simmer the soup when the cream is in it or it will curdle it.
Reheat the leftovers gently.
I like the oyster mushrooms because they have a more delicate taste than regular mushrooms and don't overpower the soup.
Makes about 6 or 8 bowls.