1. Fill a large pan with 3 ltrs cold water. Place on a medium-high heat with the lid on and bring to a simmer. Pop the porcini mushrooms in a heatproof bowl and pour over enough warm water to cover them. Soak for 2 mins, drain, rinse under cold water and tip back into the bowl. Cover with more warm water and set aside to soak while you prepare the pho.
2. Peel and thinly slice the onion and garlic. Peel the ginger, thinly slice it and then cut into thin matchsticks. Halve the chilli – you can leave in the white seeds and pith for extra heat, or scrape them out for a milder flavour. For a milder dish, leave the chilli out all together.
3. When the water in the pan is boiling, add the onion, garlic, ginger, chilli halves, star anise and cinnamon stick. Drain the porcini mushrooms and drop them in too. Add a large pinch of salt. Place the lid back on the pan and simmer on a low heat for 30 mins.
4. While the stock simmers, place the noodles in a dish. Cover with cold water and soak for 30 mins to soften them. Drain and rinse. Toss them with 1 tbsp oil and set to one side.
5. While the noodles soak, prepare your veg. Using a vegetable peeler to peel ribbons off the courgette, turning the courgette as you peel. When you get to the seeded middle, finely chop it. Trim and peel the carrots, then do the same with the carrots as you did with the courgette.
6. Remove any ragged outer leaves from the cabbage and trim the base. Finely shred the summer cabbage, including the harder centre part. This will add texture and sweetness.
7. Zest the lemon and juice it. Zest the lime but keep it separate from the lemon. Cut the lime into 6 wedges. Trim the spring onions then slice them as thinly as possible.
8. The stock should be ready by now, so scoop the star anise, cinnamon stick and chilli halves out of the pan with a slotted spoon (if you can’t find them all, don’t worry – just look out for them in your bowl). Stir in the lemon zest and juice. Add all the prepped veg to the pan and stir. Cook for 3 mins till the veg is just softened with a slight crunch. Stir through half the spring onions. Taste and add more salt if needed. Add the lime zest.
9. Divide the noodles between 6 deep bowls. Ladle over the hot vegetable pho and scatter over the remaining spring onions. Serve with wedges of lime to squeeze over.