1. For the curry paste, soak the dried shrimp and chillies in enough boiling water to just cover them, then stand for 20 minutes.

2. Once rehydrated, drain, remove and discard the chilli stems, then roughly chop the chilli, together with the shrimp, and put in a blender.

3. Using a mortar and pestle, grind the garlic, coriander seeds and coriander roots and stems (not the leaves) and salt until a rough paste forms, then add to blender. Add the shallot and tamarind and blitz to a fairly smooth paste.

4. Heat a large saucepan over high heat for 8-10 minutes, then tip in the mussels. Cover with lid and steam for 5 minutes, shaking pan a couple of times to cook evenly.

5. Strain the cooked mussels into a colander over a bowl to catch the liquor. Remove the top shells from three-quarters of the mussels, forcing any closed ones open** by slipping a butter knife between the shells. Do this over a bowl to catch any liquor and remove any stray beards.

6. Strain the mussel liquor through a fine sieve into a large saucepan over high heat. Add the stock and simmer for 1 minute before adding the curry paste. Simmer for 5 minutes, then add lime leaves, sugar and fish sauce. Simmer for a further 5 minutes, then add the celery, corn, beans and tomato and cook for 5 minutes more until the celery is tender.

7. To finish, add the mussels and simmer for 1 minute to warm through, then scatter over the coriander leaves. Serve with steamed rice.

*Note the possibility of using ham stock: it adds a lovely, smoky depth (in fact, always simmer bones and any residue from the Christmas ham to make stock for dishes such as this).

**It's often thought that unopened mussels are hazardous when, in fact, you need to worry more about the ones that are open before they're cooked. Hopefully, they'll close when you touch them, meaning they're still alive. Others are just stubborn. If they smell fresh and briny when you open them, though, they're good to go.