John Dory with potato rasam

Place a wide-bottomed pan over a medium heat and add a little olive oil and butter. Fry the chopped shallot, garlic and chilli for 2-3 minutes.Add the asafoetida, coriander, cumin, turmeric, tomato and potato trimmings to the pan and cook for a further 2-3 minutes.Add the tamarind paste and palm sugar and cook until the potato starts to soften and disintegrate. Strain off the liquid and reserve the broth.In a separate pan, boil the potato cubes in water until they begin to soften.Toast the mustard seeds in a large dry pan until they start to pop, then add the curry leaves followed by the strained broth and the potato cubes.Season with soy and black pepper to taste and leave to simmer over a low heat for 5-10 minutes. Then, add the lime juice and fresh coriander.Meanwhile, place the John Dory fillets in a steamer over a pan of simmering water and steam for 5 minutes or until cooked through. Divide the rasam across 4 plates and lay the John Dory fillets on top. Squeeze a little lime juice over the fish and serve immediately.