Cook the tomato mixture. Melt the butter in a medium saucepan over medium heat. Add the onion and sauté until translucent. Stir in the tomatoes, salt, baking soda, and thyme. Bring to a boil, then reduce the heat and simmer uncovered for about 15 minutes, until the tomatoes have broken down and the mixture has thickened.
½ cup butter, ¼ cup yellow onion, 2 (14 ½-ounce) cans diced tomatoes, 1 tsp salt, ¼ tsp baking soda, ½ tsp dried thyme
Blend and strain. Carefully puree the tomato mixture in a blender (or immersion blender) until smooth. Pour the soup through a fine mesh strainer back into the pan for the smoothest texture (you can skip this step if your soup looks smooth enough).
Add the orange juice. Stir in ½ cup of the orange juice and taste. Gradually add more until the orange flavor is noticeable but doesn't overpower the tomatoes. For a dairy-free soup, you can serve it at this point.
1 cup fresh orange juice
Finish with cream. Stir in the heavy cream and heat gently until warmed through; do not boil. Taste and adjust the salt if needed.
½ cup heavy cream
Serve. Ladle into bowls and, if desired, drizzle with additional cream and/or olive oil. Finish with freshly ground black pepper and serve with crusty bread or grilled cheese.
olive oil, fresh black pepper