Heat your oven to 200°C/Fan 180°C/Gas 6. Peel the potatoes and dice them. Trim the root and top 3cm off the leeks and halve the leeks lengthways. Rinse away any dirt under a cold tap, then thinly slice the leek. Peel the garlic and finely chop it.

Pour 1 tbsp oil into a pan and warm to a mediumlow heat. Slide in the chopped potatoes, leeks and garlic. Stir in a pinch of salt and pepper. Pour over 100ml boiling water. Cover with a lid and cook for 20 mins, stirring occasionally, till the potatoes are tender. Add an extra 1 tbsp water if the veg starts to catch on the bottom of the pan.

Meanwhile, make the sorrel butter. Finely chop the sorrel and slide into a small bowl. Zest in the lemon and sprinkle in a little salt and pepper. Tip in the butter, and mash everything together with a fork till well combined. Set aside.

Snap the ends off the asparagus (bend the spears and they’ll break at the right point). Discard the woody ends. Trim the roots off the spring onions. Slice into 5cm chunks, green and white parts.

Line a large baking tray with greaseproof paper. Pop the pollock fillets onto the tray. Dollop half the sorrel butter onto each fillet. Slide the fish into the oven and roast for 6 mins.

After 6 mins, arrange the asparagus and spring onions around the pollock. Roll the asparagus around in the butter that has melted off the fish. Return the pan to the oven for a further 6 mins, till the fish flakes easily when touched.

Taste the potatoes and leeks, and add a little salt and pepper if needed. Squeeze in the lemon juice. Spoon the potatoes and veg onto plates and top with the roasted vegetables and herb-topped pollock fillets. Drizzle over any buttery pan juices and serve straight away.