Peel and finely slice the onion. Peel the kohlrabi, trimming off any stems. Finely slice the kohlrabi into rounds, then slice those into short lengths. Pop in a bowl of cold water.
Peel the ginger and slice it into matchsticks. Finely slice the chilli into rounds – flick out the seeds and white bits if you want less heat. Finely grate the zest from the lime. Juice it. Fill the kettle and boil it.
Measure out 1 tbsp of the Demerara sugar and add it to the lime juice. Measure out 1 tbsp of the tamari and add that too. Stir for a few mins to dissolve the sugar. Put the dressing to one side.
Warm ½ tbsp olive oil in a frying pan. Add the sliced onion. Fry over a low heat for 8-10 mins till the onion is soft but not too coloured. Stir every so often.
While the onion cooks, arrange the salad leaves on two plates or one large platter. Fill a large pan with hot water from the kettle. Bring to the boil.
Add 2 bundles of the noodles to the pan. Lower the heat and simmer for 3-4 mins till they're just cooked. Drain and rinse under cold water to cool. Tip back into the pan. Add ½ tbsp oil. Toss to mix.
Lift the onions from the pan. Scatter them on the salad leaves with the noodles. Add the ginger to the
pan. Stir and fry for 30 secs. Add the beef. Stir-fry for 5-8 mins till the beef is browned and cooked.
Arrange the beef on top of the salad. Drain the kohlrabi and add to the salad. Scatter over the chillies. Drizzle over the dressing and serve.