Rasam is a sour, soupy, thin, tamarind-based broth with tempered spices, maybe some vegetables, perhaps some lentils, usually seasoned with a lot of pepper.

In Sri Lanka it’s often served before a meal in a glass or cup to whet the appetite and awaken the taste buds, or it’s served alongside thosai and dosa for dipping, or with rice. It’s versatile and quick and oh so good for you. Here, I’ve turned it into an easy meal, with mussels gently simmered in the broth. All you need is some roti or rice on the side to mop up the juices.

O Tama Carey. Photograph: Patricia Niven

Note: if you’ve heard a dirty rumour that if a mollusc doesn’t pop open when cooking it is bad, know this is not always the case. The smell of off molluscs or shellfish is usually so distinctive it will be painfully apparent before you even cook it. Saying that, though, if you ever encounter an unopened shell among the popped ones, use a fork to gently prise it open and have a gentle sniff. If it is bad, you will know immediately.

O Tama Carey’s mussels in rasam – recipe

Serves 2–4

100g French green lentils 40g tamarind pulp 1 bunch coriander, leaves picked and washed, to garnish; stems and root washed and finely chopped 15g peeled ginger, finely chopped 15g garlic cloves, finely chopped Salt flakes 100g ghee 4g coriander seeds 1g mustard seeds 1g cumin seeds 3g chilli powder 2g turmeric powder 3g curry leaves 150g cherry tomatoes, halved White pepper 1kg mussels

Place the lentils into a saucepan, generously cover with cold water and bring to a boil. Simmer for two minutes, then strain and set aside.

Next, prepare your tamarind. Soak the pulp in 70ml boiling water for 30 minutes, then push it through a fine strainer. Set aside.

Use a mortar and pestle to grind the coriander stems and root, ginger and garlic into a paste; use a little salt to help with this. Set aside.

Place a wide-based saucepan with a lid – large enough to hold the mussels – over a medium heat and add in the ghee. Allow it to warm before adding in the spices. Stir and cook the spices for about one minute, until they start to toast and sizzle, then add the curry leaves and fry them for another 30 seconds or so.

Add the coriander paste and cook, stirring for another minute, then add the cherry tomatoes and season well with white pepper. Give the tomatoes a few moments in the pan before adding the tamarind, lentils and 300ml of water. Bring to a boil, then turn the heat down to very low and allow to gently cook for 10 minutes.

Have a taste and season a little more if needed. The flavour should be sour with richness from the ghee, and I like it to be quite peppery.

Add in your mussels, give everything a good stir, increase the heat to medium and put the lid on your saucepan. The mussels should cook fairly quickly, in around three minutes. You’ll know they’re done once they have mostly popped open.

Serve in a bowl or straight from the pot, garnished with the coriander leaves.