Canning Soup Base and Tomato Sweet Potato Soup with Rosemary

Here we are again, cooking the last of a season and the first of the next: tomatoes out, sweet potatoes in. The fact that I had 12-15 pounds of tomatoes and 12-15 pounds of sweet potatoes in my house at the same time led me to the logical conclusion.

Today, I am determined to consume or preserve the last of the tomatoes, other than a few fresh ones that are still in good condition. I still had about 10 quarts of tomatoes to go… mostly paste tomatoes but some heirlooms and some field tomatoes and some cherry tomatoes. I’ve canned enough tomatoes and tomato-based concoction to last the year and frankly, I’m just ready to get rid of the lot.  I took the “lazy” way out (if you can call any canning venture lazy). I roasted the cherry tomatoes in abundant oil, garlic and rosemary and poured them into a large jar that will be stored in the refrigerator. I’ll be fishing them out for various uses for a month or so. Then I roasted halved plum tomatoes, skimming off the liquid and reducing them to a dry, almost leathery state. They’ll be reunited with some of the liquid and frozen in small bags.  And then there was the rest.

I made two types of soup base: one with peeled and seeded organic plum dandy paste tomatoes, and the other a mix of every type of tomato I had, chopped with skin and seeds and all. Both bases began were with chopped onion cooked slowly in a little olive oil until translucent and, once the tomatoes were added to the pot, lightly salted and boiled fast for 10 minutes to render their juice before simmering for 45 minutes. I used an immersion blender to smooth the mixture and canned it in quart jars (with 2 tbsp lemon juice added) for 30 minutes. I actually liked the mixed tomatoes better since many were riper and more flavorful than the paste tomatoes.   

I reserved about a quart of mixed tomato puree to make into two soups: cream of tomato and tomato sweet potato soup with rosemary. A sprig of rosemary gave this flavorful soup a piney inflection, cutting the natural sweetness of the vegetables.

Tomato Sweet Potato Soup with Rosemary

1 medium onion, chopped

2 tsp olive oil or a combination of olive oil and butter

1 lb (2 medium) sweet potatoes, peeled and cubed

1½ -2 c chicken stock or vegetable broth

2–2½ c tomato soup base (or canned tomatoes, chopped, or fresh tomatoes)

Sprig of rosemary


Optional: a pinch of red pepper flakes, paprika or pimenton (smoked paprika)

Garnish: cream, rosemary croutons

In a saucepan over medium low heat, slowly sauté the onion in olive oil and/or butter until translucent. Increase the heat slightly, add the cubed sweet potatoes and stir them to cook and slightly brown. Add the liquid and bring the mixture to a boil. Add the tomatoes, rosemary and a little salt (unless you’re using canned tomatoes), and look slowly until the sweet potatoes are very tender, 30-40 minutes. Remove the sprig of rosemary and puree the soup using a food processor or immersion blender. Serve hot with rosemary croutons and a little cream, if desired.

Serves 4.

Categories: Preserving, Soup, Sweet potato, TomatoTags:

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