4 cups hot tomato soup base
1 cup hot white sauce
These are some versions that I tried:
- hot, thickened tomatoes poured into cold milk (curdled)
- hot thickened tomatoes poured into hot milk (curdled)
- cold milk added to hot, thickened tomatoes (no note written down, but I bet it curdled)
Then, my friend Jan told me that the acid (tomato) and base (milk) must be similar amounts, and the acid must be added to the base.
However, I was not fond of the pale pink tomato soup that resulted from so much milk added. Rebecca started messing around in her lab (kitchen) and reporting results. I started independent testing to verify her results in my lab (kitchen), with the results verified by a consumer panel (family).
Look, if tomato soup curdles, it's still tasty. It's just that the milk turns into sticky little curds and the soup looks freckled, not creamy. I've never actually thrown out a test batches, just grumbled my way through it.
Last summer, following Rebecca's method, I made and canned tomato soup base. It's tomatoes cooked with onions, celery, and salt, and then pureed. (Right, Rebecca? I can't find anything I wrote down anywhere, so I'm going on my paltry memory)
To make tomato soup, I simply heat a quart jar of this tomato soup base while I'm making a white sauce in a saucepan. 1-2 Tbsp. butter, melted (maybe a little mushroom or onion in here if you like), with 1-2 Tbsp. flour whisked in and then cooked together until bubbly. 1 cup warm milk whisked in and whisk whisk whisk over medium-low heat until it steams and thickens.
I usually prefer straightforward cream of tomato soup, but you can add some basil or other herbs, a little cooked rice, or, as mentioned above, something like mushrooms, onions, garlic, or celery in the white sauce.
Serve with crackers, grilled cheese sandwiches, or cheese quesadillas.
Just to muddy the research, how do you make homemade cream of tomato soup?