Heat oil in a flat pan and sauté mustard seeds and curry leaves until they pop.
Add ginger, garlic, chillies, and onions, then sauté until translucent and stir in ground spices.
Add 120ml water and tamarind, simmer, then stir in coconut milk and salt until thick.
Boil the peeled potatoes in salted water until tender, then drain.
Sauté ginger, lentils, and mustard seeds in oil, then mix with crushed potatoes and curry leaves.
Pan-fry the sea bass fillets in hot oil until the skin is crisp.
Mix the cresses together and dress with a small amount of curry leaf oil.
Plate the potatoes, surround with sauce, top with fish and garnish with cress salad.