• Preheat your oven to 220°C/200°C fan/gas mark 7. Boil a large pot of salted water.
• Chop the potatoes into 2cm chunks (peeling optional). 
• Add the potatoes to the boiling water and cook until fork tender, 12-18 mins. Reserve 4 tbsp of starchy cooking water then drain and return to the pot, off the heat.
• Trim the root and the dark green leafy part from the leek. Halve lengthways, then thinly slice.
• Place a pan over medium heat with a knob of butter. Cook the leek until softened, 6-8 mins. Remove from the pan and set aside.

• Meanwhile, peel and grate the garlic (or use a garlic press).
• Pat the basa with kitchen paper. Lay into an appropriately-sized oven dish (this dish will be used later for the brandade). IMPORTANT: Wash hands and equipment after handling raw fish. Fish is cooked when opaque in the middle.
• Drizzle with oil and season with garlic, salt and pepper.
• When the oven is hot, bake on the top shelf until cooked through, 10-15 mins.

• Meanwhile, mash the potatoes with half the apple cider vinegar, creme fraiche, reserved cooking water and a knob of butter. Add the stock and season to taste with salt and pepper. 
• Using a fork, break the fish slightly and carefully mix with the mash along with the leek.
• Mix the breadcrumbs and cheese in a separate small bowl. Season to taste with salt and pepper.

TIP: Leave a few larger pieces of fish to enhance texture of the brandade.

• Place the brandade in the oven dish.
• Sprinkle the cheese and breadcrumb mix over the top. Drizzle over a little oil.
• Bake on the top shelf until the brandade is nicely coloured, 10-12 mins.

• When everything is almost ready, toss the salad leaves with the remaining apple cider vinegar and a drizzle of oil.
• Season to taste with salt and pepper. 

• Divide the crispy brandade between plates. 
• Serve the dressed salad leaves alongside.