In a large soup pot over medium heat, warm olive oil. Add onion and sauté until soft and translucent, about 12 minutes. Add garlic and continue to cook for 1-2 minutes or until garlic becomes fragrant. Add tomatoes, thyme, and vegetable broth. Simmer, covered for about 20 minutes. Remove from the heat and let cool slightly. Add in the sour cream. Using a food processor or immersion blender blend together until smooth with a few chunky pieces. Add sea salt and pepper to taste.