Black Mustard Soup

This black mustard soup recipe came about from wandering. Wandering carefree through the hedge.

For a few days, I have been walking past black mustard (Brassica nigra).

The delicate little flower buds gracefully adorning tender stems called out to me.

“Use me like little broccoli florets”, they sang.

And because I have been immersing myself in the history of Japanese food, a flash came to mind.

How perfect to include these little yellow-green buds in a thin, temple cuisine black mustard soup.

The base would be a stock (called dashi) which is traditionally made from kelp seaweed. It’s very simple to prepare.

I also decided to add some shiitake mushrooms to add more depth. Finding I didn’t have any in my cupboard, and being short on time I settled for porcini instead.

The idea was to make the dashi, serve it with shredded kelp seaweed, a few porcini mushrooms and topped with steamed black mustard flower buds and stems.

Only three ingredients make up with black mustard soup recipe. OK, four if you count the water.

Don’t get fixated on having to use specifically black mustard. Any wild mustard will do.

If you like simple, minimalist, plant-based cooking. This recipe is packed with umami flavour and is deeply nourishing.

Black Mustard Soup Recipe


  • 50 g dried kelp seaweed (cut into strips)
  • 30 g of dried porcini mushrooms
  • 50 g of black mustard flower buds and tender stems
  • 1 litre of water


  1. In a pan bring 1 litre of water to the boil, then add the dried porcini mushrooms, and kelp seaweed.
  2. Reduce the heat to a low simmer, and cook for 20 minutes.
  3. Turn off the heat and allow the ingredients to infuse for a minimum of one hour. Longer if possible.
  4. Strain the liquid out reserving the seaweed and mushrooms. It will most likely have reduced by half, so you’ll end up with around 500ml.
  5. Steam the black mustard flower buds for 3 minutes.
  6. While they are steaming, shred the kelp into strips and put in a soup bowl, along with some of the mushrooms. How much is entirely up to you.
  7. Pour some of the dashi stock over them. If it is too cold gently re-heat. I like my dashi very strong, but this can be pretty overpowering for some people, so top up with some of the cooking water to your desired taste.
  8. Finally, place the steamed black mustard greens on top, and serve.

Serves: 2


  1. Tasty, easy recipe. I used the flowering tops of rape, which is growing wild around where I live. Also added some pieces of tofu. Finally added a little miso after taking soup of the heat. Yum. Thanks for the inspiration.

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