1 Rinse the fish fillets, pat dry and cut into bite-sized pieces. Peel the garlic and onion and cut into small cubes. Peel the ginger and finely grate. Season the fish with salt and pepper and coat with flour.
2 In a pan, melt the butter and cook the fish cubes until golden brown and cooked through, about 5 minutes on each side. Remove and set aside. Add the garlic and onion to the pan and sauté 2 minutes. Add turmeric, chili powder, ginger and tomato paste and sauté for another 2 minutes; deglaze with fish stock.
3 Place the fish in the sauce and gently simmer until cooked through, about 5 minutes. Season with salt, pepper, mustard and lemon juice. Serve the curry in bowls and if desired, garnish with cilantro leaves.