Spice-crusted black cod, onion sauce, shiitake and asparagus

For the onion sauce, place a large saucepan over a medium-high heat and add the oil. Once the oil is hot, add the onions and cook until well browned, stirring occasionally

Remove the browned onions and drain on paper towel. Add to a clean saucepan along with the fish or vegetable stock and freshly ground black peppercorns. Simmer for 15 minutes, then strain into a small saucepan and set aside

Flash-fry the leek slices in hot oil until golden brown, then remove and drain on paper towel. Set aside until required

To prepare the cod, cut the fillet into 4 portions and set aside. Dry-roast the spices in a pan, then grind in a spice-grinder (or using a mortar and pestle) until a coarse powder forms. Sprinkle the spice powder onto the cod fillets and set aside

Preheat the oven to 200°C/gas mark 6

Place a non-stick pan over a medium-high heat and add the butter. Season the spiced cod with salt and cook in the pan for 2 minutes on each side

Line a baking tray with parchment paper and carefully transfer the seared cod to the tray. Add the asparagus and shiitake mushrooms, drizzle with vegetable oil and finish cooking in the oven for 4-5 minutes, or until the cod is cooked to your liking

Meanwhile, bring the onion sauce to the boil. Mix together the cornflour with a teaspoon of cold water and add to the boiling sauce to thicken. Season with salt and check the seasoning

To serve, place each fillet of cod in the middle of a soup plate and arrange the asparagus and mushrooms alongside. Pour over the onion sauce and garnish with the crispy fried leeks. Serve immediately