Place the barley in a suitable-sized sterilized container and pour 600 milliliters/two and 1/2 cups of cold water over the grains. Stir with a clean sterilized spoon, then cover the container with muslin. Keep in a warm place and allow to ferment for four days, after which time the barley will be ready to use. (It can then be stored, in the liquid, in an airtight container in the fridge for up to five days.)

Drain the barley, add to a large saucepan with the stock and set over medium heat. Bring to the boil and simmer for 20–30 minutes until it is tender but retains its bite.

Meanwhile, toast the walnuts in a dry frying pan/skillet set over a medium heat.

Heat the walnut oil in a separate frying pan/skillet and add the mushrooms and garlic. Fry until golden, then season with salt and pepper. Stir in the rosemary and chilli/hot red pepper flakes. Pour the mixture into a bowl and put the pan back on the stove to make the dressing.

To make the dressing, put the spring onions/scallions, walnut oil, balsamic vinegar, and lemon juice in the pan and stir until well combined. Set the pan over low heat and cook until the mixture bubbles. Remove from the heat, season with salt and pepper and stir in the parsley.

To assemble the salad, put the salad leaves in a large bowl with the mushrooms and pearl barley and stir in the dressing. Toss to combine, spoon into serving bowls and serve immediately.