In a large stock pot, melt butter in vegetable oil over medium heat. Add onion, sprinkle in ½ teaspoon salt and pepper and cook for 5 minutes, until onion begins to become translucent and brown a little.

Add in garlic, cooking until fragrant, about 1 minute. Mix in tomato paste and stir in well, then pour in tomatoes and their juice, chicken broth, water, baking soda and herbs.Stir together well, turn heat up to high, bring to a boil.

After soup begins to boil, turn heat down to medium low to simmer, cover pot with lid, and simmer for 30 mins. After 30 mins, season with salt, pepper, and sugar to taste. Start with 2 teaspoon of sugar and work up to your preferred sweetness.

Using an immersion blender or regular blender (spoon in small batches, blend, then pour into a large bowl, if using regular blender), blend the onions and tomatoes smooth.

Use a chinois, china cap, or mesh sieve to strain the soup of the skin and seeds into a separate large bowl. Get a rubber spatula to press remaining liquid out of the solids.

Pour heavy cream into bowl of soup, if desired.

Serve hot.