Puree the onion until completely smooth, then squeeze it through a fine sieve or cloth to remove as much liquid as possible, leaving behind the concentrated onion pulp.

Transfer the onion pulp to a large mixing bowl and combine it with the lamb, yoghurt, olive oil, garlic, salt, paprika, cumin, cayenne, and black pepper. Mix thoroughly with your hands or a firm spoon until the mixture is sticky and uniform.

Place a sheet of baking paper on a flat surface. Spread the mixture on top and flatten it slightly with your hands or a rolling pin so it is thin enough to roll.

Place another sheet of baking paper on top of the flattened mixture to prevent sticking, then carefully roll it into a tight log using the top sheet to guide and compress it.

Preheat the oven to 180°C. Transfer the rolled doner onto a tray and bake for 8–10 minutes, or until fully cooked through but still tender.

Allow it to rest briefly, then tear or cut the cooked sheet into pieces. Serve warm with naan or your preferred sides.