Preheat your oven to 220°C/200°C fan/gas mark 7.

Pop a large saucepan of water with ½ tsp salt on to boil for the potatoes. Chop the potatoes into 2cm chunks (peel first if you prefer).

Trim the carrots (no need to peel). Chop into roughly 1cm wide, 5cm long batons.

Halve, peel and thinly slice the shallot. Peel and grate the garlic (or use a garlic press).

Pop the carrots onto a baking tray. Drizzle with oil, season with salt and pepper then toss to coat.

When the oven is hot, roast on the middle shelf until tender, 25-30 mins.

When your pan of water is boiling, add the potatoes and cook until you can easily slip a knife through, 15-20 mins.

Meanwhile, in a small bowl, pop the breadcrumbs, pesto and olive oil for the crumb (see pantry for amount) and mix together.

Pat the cod dry with kitchen paper.

Lay the cod onto a lined baking tray. Spread the mayonnaise over the top of the fish and top with the breadcrumb mixture. Press it down with a spoon.

When the oven is hot, bake on the top shelf until the crumbs are golden and the fish is cooked through, 10-15 mins. IMPORTANT: Wash your hands and equipment after handling raw fish. It's cooked when opaque in the middle.

Meanwhile, heat a drizzle of oil in a medium frying pan on medium heat.

Once hot, add the shallot and stir-fry until softened, 3-4 mins. Stir in the garlic and cook for 1 min. Add the cider vinegar and allow it to evaporate, 1-2 mins.

Pour in the water for the sauce (see pantry for amount) and vegetable stock paste, then bring to the boil and simmer until reduced by half, 2-3 mins.

Vigorously stir in the butter (see pantry for amount) until melted, then remove from the heat.

Once the potatoes are cooked, drain in a colander and return to the pan, off the heat. Add a knob of butter and a splash of milk (if you have any) and mash until smooth. Season to taste with salt and pepper.

Serve the cod with the mash and roasted carrots alongside.

Spoon over the sauce to finish.