This is absolutely my favorite soup to make (and eat!). It's delicious hot or cold -- so it's versatile for any season. I can't wait until my heirlooms are ready to pick, and I can make it again. It's a little labor-intensive, but so very worth it. As usual, I don't write official recipes, but will tell you about my method.
I quarter the tomatoes, slice some onions (shallots would be great here, too, but I use sweet onions), add some whole garlic cloves, and throw them into an oven with olive oil, thyme, salt and pepper.
I roast them until the onions are soft...
Then I add chicken stock, puree everything with a stick blender, and strain it twice. The result -- a sweet, savory and silky bisque. Lovely by itself or with bread to sop it up -- you won't want to leave a drop. =)