Peel and roughly chop the garlic and ginger. Pop them in a small food processor. Roughly chop the chilli (for less heat, halve and scoop out the seeds and white pith). Add it to the ginger and garlic. Add 2 tbsp Thai red curry paste, 2 tbsp water and blitz to make a chilli curry paste. No food processor? Grate the garlic and ginger and finely chop the chillies, then stir everything together. Set aside.
Peel and finely slice the onion. Halve the pepper, scooping out the seeds and white pith. Finely slice the pepper into long lengths. Trim the ends from the courgette, halve it and slice it into 1cm-thick half-moons. Scrub the potatoes and chop them into 1cm-thick rounds.
Warm a large wok, deep frying pan or casserole dish over a high heat for 2 mins. Add 2 tbsp oil and the chilli curry paste. Stir fry for 30 secs.
Add the onion, pepper and courgette to the pan. Stir fry for 5 mins till the veg have started to soften or brown. Add the potatoes to the pan.
Crumble in the stock cube. Add 1 tbsp of the Worcester sauce. Pour in the coconut milk. Add 450ml boiling water and a pinch of salt. Pop a lid on the pan (or use a baking tray if you don’t have a lid) and simmer for 12-15 mins till the potatoes are almost tender all the way through.
While the curry simmers, separate the spring green leaves and slice out any thick cores. Finely shred the leaves into ribbons.
Stir the spring green ribbons into the pan. Simmer, without the lid on, for 5 mins till the potatoes are cooked all the way through and the spring greens are just tender.
Taste the curry and add a pinch more salt or a dash of Worcester sauce if you think it needs it. Ladle the curry into warm bowls to serve.