Instructions

Step 1: Preheat the oven to 190°C/375°F/gas 5.

Step 2: Scrub the sweet potato, then slice into thin rounds. Arrange the slices, overlapping, in a large roasting tin.

Step 3: Bruise the lemongrass, then finely chop the tender parts. Peel and finely chop the ginger and garlic. Finely slice the chilli.

Step 4: Mix the sesame oil, stock, coconut milk and two-thirds each of the lemongrass, ginger and garlic. Pour over the potatoes, tuck in the lime leaves (or squeeze the juice on top and scatter over the zest) and sprinkle over the chilli.

Step 5: Roast for 20 to 25 minutes, or until the potatoes are done. About 8 to 10 minutes before the cooking time is up, sit the Cobia on the potatoes and top with the rest of the lemongrass, ginger and garlic.

Step 6: When the Cobia is just cooked, drizzle with soy sauce, if you like. Delicious served with green beans and mangetout.

Ingredients

• 1 large, sweet potato
• 2 sticks of lemongrass
• 2.5 cm piece of ginger
• 2 cloves of garlic
• 1 teaspoon sesame oil
• 150 ml vegetable stock
• 150 ml light coconut milk
• 6-8 lime leaves or 1 lime
• 1 long red chilli
• 4 6oz Cobia fillets