- Preheat the oven 200ºC/180ºC fan/gas 6.
- Place a potato in the bevel of a wooden spoon. Using a sharp knife, make thin incisions all along the potato without going all the way through. Repeat for all of the potatoes before placing in a baking tray.
- Drizzle the oil over the potatoes and generously season with salt and pepper. Turn each potato, cut-side down, and roast in the oven for 30 minutes.
- Remove the potatoes from the oven and turn cut-side up. Roast for another 15 minutes.
- Remove the potatoes once again and sprinkle first with the grated Cheddar, then the diced chorizo*. Return to the oven for a final 10 minutes until the Cheddar has melted and the chorizo is crisp.
- In the meantime, make the dip. Combine the soured cream, mayonnaise and chives in a bowl and season generously with salt and pepper.
- Serve the potatoes straight from the oven, and spoon the dip into a small serving bowl. Finish with a generous sprinkling of freshly chopped chives.
*Make this dish vegetarian by switching chorizo for 100g roasted red pepper. Simply drain from the jar, rinse and dice. Sprinkle over the potatoes along with the Cheddar for the final 10 minutes of cooking.