Get a bowl of iced water ready. Bring a pan of salted water to the boil, add the green beans and cook for 2-3 mins until bright green but still crunchy. Use a slotted spoon to remove the beans and plunge them into the ice water. Add the spinach to the boiling water and cook for 20-30 secs, then remove and add to the ice water. Once cool, drain the greens in a sieve over the bowl and set aside for 5 mins so that all the water drips out of them.

Make the dressing by grinding the sesame seeds with a pestle and mortar or spice grinder, then mix in the other ingredients. Toss the greens in the dressing, top with the gomashio, if using, and serve.