In a heavy, medium saucepan or a Dutch oven, bring the vegetable broth, tomato puree, onion and cloves to a simmer. Partially cover and cook for 20 minutes.
Strain the soup through a sieve into a large bowl. Season with salt and whisk in 1/2 cup creme fraiche. Place in another bowl filled with ice to cool. Refrigerate until chilled, about 30 minutes. Serve in shot glasses, dollop with more creme fraiche.