Fill your kettle and boil it. Peel and finely chop the onion. Trim, peel and finely chop the carrots. Trim the roots and top 3cm off the leek. Halve it, rinse out any grit and finely slice it.

Place a pan on the heat for 2 mins then add 1 tbsp oil. Add the chopped veg and cook for 5 mins, stirring now and then, till starting to soften.

Meanwhile, peel and grate the ginger, garlic and turmeric (turmeric likes to stain things yellow, so grate it onto a plate or a chopping board you can wash straight away and protect your clothes with an apron and your fingers with gloves). Squeeze the miso into a jug and pour over 800ml hot water from the kettle. Stir to dissolve the miso.

Add the garlic, ginger and turmeric to the pan and cook, stirring, for 1 min. Pour in the miso stock. Simmer for 5 mins.

Meanwhile, snap the noodles into 2cm-long lengths. Zest the lime, then cut it into quarters. Slice the chilli into thin rounds, flicking out the hot seeds if you prefer.

Add the noodles to the broth and simmer for 3 mins till they are tender. Stir in the lime zest, half the chilli and half the watercress. Stir to wilt the watercress.

Taste the soup and add some salt if you think it needs it. Ladle into warm bowls, top with a large handful of watercress, the remaining chilli and serve with a couple of lime wedges each.