In a stock pot or Dutch oven, melt the butter. Add the onion, celery, and smashed garlic. Simmer over moderate heat, stirring occasionally, until the onions are translucent—about 5 minutes.
Add the tomatoes as well as their juices, vegetable broth, heavy cream, sugar, oregano, salt, and pepper. Bring the soup to a rolling boil over high heat and break up the tomatoes with a spoon or spatula. Reduce the heat to medium-low and simmer for 10 minutes.
Carefully transfer the soup mixture to a powerful blender or food processor (you'll have to do this in batches), and blend until velvety smooth. Once all the soup is smooth, return it to its original stock pot. Taste and adjust seasoning. If you find the soup on the acidic side, bring it to a simmer, add the baking soda, and wait for it to foam and fizzle. Stir it, and let it simmer for about five minutes. Taste. You should have a smoother and much less acidic flavor now.