A tasty, hearty, and yet simple and no-frills soup, created with nothing more than a carefully-selected local stone and water.

On the blog we get a lot of questions about how to combine various ingredients that you might have in your pantry. Last week we had a postcard from a Mrs Trellis of North Wales, whose son had dug up a large and unusually beautiful hunk of granite from the garden, and wanted to know if we had any culinary tips. Well, Mrs Trellis, we do indeed. Stone soup is one of the easiest traditions in our kitchen, and we’re going to show you how it’s made.

You might not think that a billion-year-old geological formation would be a vital tool in the home cook’s arsenal. Surprisingly, almost all culinary traditions have some variation on stone cooking. The limestone quarries of Britain were the crucible for many Roman dishes – conscripted legions passed the time between sorties by hacking off lumps of the calcite-rich landscape and frying them up with wild garlic and flatbreads (see Gibbon’s Decline and Fall, chapter IV, subsection I, for more details of this practice, especially as detailed in the writings of Aprilus Asinus).

Igneous cairns in Scotland and their neighboring islands to the North were often plundered for their bounty. Icelandic epic poems, such as the Njals Saga, tell us how vital were pumice and scoria to the trading routes across the North Sea. Obsidian was a harder sell, but even that could be combined with local mushrooms to form a hearty broth that could fill a Viking’s stomach. In more modern times, the Swedish-Norwegian War of 1814 was triggered by a dispute between two villages, on either side of the border, as to what color of basalt made the better risotto. (The correct answer is, of course, brown. Sorry, Gottskår.)

So there’s a lot of history associated with the culinary use of rocks. You’ll have noticed a big variation in the types of mineral that work best with local flavors. Your local geology society will be able to give you more information, but there’s no harm in starting with whatever you find in your own back yard. Just a few tips:

  • Stick with natural rocks. Concrete and cement block contain a lot of artificial flavors and preservatives.
  • Avoid anything too small that you might accidentally swallow. Don’t even think of using gravel. We prefer to use stones of at least 8 inches in diameter, maxing out at whatever will fit in our stockpot. Don’t feel like you have to go silly in the other direction; if you can’t carry it into the kitchen without throwing out your back, there’s no point trying to make soup out of it.
  • We recommend you start with soup, since it’s the easiest method for a beginner to get to grips with. Later, you can advance to more complex recipes such as stone cake, stone soufflé, and stones served up with liver and a nice Chanti.

 

Let’s get stuck in! Hopefully by now you will have selected your rock, optionally given it a ceremonial name (I recommend “Scrimshaw, Destroyer of Worlds”) and given it a decent scrub to get off the worst of nature’s grime. Now, just as important as the choice of stone is the quality of your tap water. You may think “aha! I’ll just use a filter jug”, but think again. You’re trying to filter out calcium, iron and other flavors with one hand, while simply adding them back when you drop in the stone. So just go with plain old tap water. Unless your local city water is filthy or particularly foul-tasting, in which case please use Pellegrino or Fiji Water.

Fill your pot up to about 2 quarts with the water, and carefully drop in the stone. On a low-medium flame, bring the water up to a simmer, and maintain the temperature while you stir. Add a generous pinch of salt and some cracked black pepper. Continue to cook, stirring and tasting every once in a while. You can use whatever you like to stir – we happened to have a ham hock to hand. To give the soup a little color, we diced up some carrots, celery and onions, and threw them into the pot. If you need a thicker broth, you can chop up some potatoes or throw in some peas, both of which supply a good starchy base.

After about half an hour, you can discard your stirring utensil, taste one more time, turn down the heat and add any final flavorings you feel it needs (you might try a little creme fraiche or coconut milk). We also had a few fresh shrimp which we added at this point and cooked through just long enough to turn pink.

Finally, remove and discard your stone. Most municipal recycling facilities will not accept stones, but you can usually bury it in the garden where you found it, and, after a year or two of maturation, dig it back up for another round of soup-making. We’ve found the flavor fades after three or four rounds.

I hope you’ve had fun following along, please let us know if your own stone soup was a success, and if not, let us know. We’ve probably made the same mistakes as you, and there’s no shame in that. Happy April 1.

Stone Soup
 
Prep time
Cook time
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Author:
Serves: Serves 6
Ingredients
  • One (cleaned) stone, approx 10 inches in diameter
  • 2 quarts water
Instructions
  1. Place stone and water in a large (4 quart or larger) stock pot.
  2. Bring water to a simmer and maintain low heat for 30-40 minutes. Stir as needed and taste (see article for items we used to stir soup). When ready, remove and discard the stone and ladle soup into separate bowls.
  3. You can refrigerate or freeze any leftover soup.