Roasting the cubed potatoes until golden adds deep flavor to this soup. You can stir in a bit of heavy cream in place of the sour cream, or add a handful of grated cheddar to the hot soup. It's also delicious with some crumbled bacon on top.
Heat the oven to 450 degrees F. Spread the potatoes, onion, and garlic cloves on a large cookie sheet and toss with the oil to coat. Spread them in one layer and sprinkle with salt, pepper, and thyme. Roast for 20 minutes. I have a gas oven, so I put them on the bottom rack for maximum browning. Put them on whichever rack in your oven that will ensure a good, golden crust.
Once the potatoes are well browned on one side, Carefully flip each piece so that youâll get even browning and put them back in for another 20 minutes. Or, if youâre not crazily obsessed like I am, just give them a stir and roast until done. (Yes, I really do turn each piece. Itâs my personal brand of OCD behavior.)
When you have achieved golden goodness, set aside the garlic cloves and scrape the rest into a stockpot. Add chicken stock (or veggie stock) to cover and set the pot over medium heat. I like to pour some of the stock on the cookie sheet to loosen some of those great browned bits, then add that liquid to the pot. Squeeze the roasted garlic out of the skins, mash it up a bit, and add it to the pot.