Melt the butter in a Dutch oven or soup pot. Once butter is hot, add onion. Saute over medium heat 8-10 minutes. Add salt and garlic. Saute 1-2 minutes.
Add tomatoes, chicken stock, 1 tbsp sugar, baking soda, and herb bouquet. Bring to a boil. Reduce heat to simmer. Cook 30-40 minutes, stirring occasionally. If time, cook longer to reduce acidity and get a sweeter soup, up to 2 hours.
Remove herb bouquet. Transfer soup to blender and puree, working in batches if needed. Return pureed soup to pot and bring to boil, then reduce heat to a simmer. Taste and add more salt and sugar if desired. Let simmer until soup is at desired consistency, 10-20 minutes more. Remove from heat. Add cream and a sprinkling of freshly ground pepper.
Serve with fresh, crusty bread or crunchy croutons.