I found this recipe in Great Grandmother’s Recipe Book, (page 26) published in England in 1900. The implication is that it is a considerably older recipe. Oddly enough, this is probably the only rhubarb soup recipe I’ve ever seen in an old cookbook. It caught my eye because we have a big thriving patch of rhubarb and I wanted to use some without having to add sugar.
The soup was really quite tasty, I thought. It’s definitely sour! I’m not sure I would have been able to identify it as rhubarb if I hadn’t known that it was, even though the soup turned out to be a pretty shade of rhubarb pink. I used the reddest stalks I could find, most of which were red right through. If they are green in the centre I’m sure the colour will not turn out so well.
The recipe called for a small piece of ham. Old recipes seem quite convinced that all soup must taste of meat. I didn’t have any, and I was serving this with pork chops, so ham seemed redundant anyway. You could try putting in a little if you liked, but it was fine without it. More unusually for an old recipe, it called for seasoning with Cayenne. I decided to just use a generous amount of black pepper, but I think Cayenne might have balanced out the sourness of the soup better. As usual, I changed the recipe a fair bit, but I think it still gives the feeling of the original. They did serve it with croutons, and if you had some I think they could be quite nice. This is a starter soup though, best in quite small portions to introduce another course. I wouldn’t try to serve it as the basis of a meal
4 to 6 servings
30 minutes prep time
3 cups finely diced red rhubarb stems
1 small onion, preferably red
1 small carrot
3 tablespoons unsalted butter
1/4 teaspoon salt
freshly ground black pepper OR ground Cayenne chile to taste
3 cups unsalted chicken OR vegetable stock
2 teaspoons arrowroot or corn starch
Wash, trim, and dice the rhubarb. Peel and dice the onion. Peel and finely dice or grate the carrot.
Heat the butter in a heavy-bottomed soup pot over medium heat. Add the rhubarb, onion, and carrot and cook, cover on, for about 10 minutes, until very soft. Stir occasionally. Season with the salt and pepper.
Add 2 cups of the stock – holding back 1 cup – and simmer for a few minutes, then transfer it all to a blender or food processor and blend until very smooth. Return it to the soup pot. Mix the starch into the remaining cold stock, and use it to swish out the blender before pouring it into the soup. Simmer until the soup thickens; just a few minutes. Serve at once.