Dice your potatoes into 1-inch chunks for even cooking. Slice your onion into thin strips, grate your garlic and ginger, and finely dice your green chilli. Roughly chop your fresh coriander.

Place your diced potatoes in a medium-sized pan of water. Season generously with salt and bring the water to a boil. Reduce the heat to a simmer and cook for about 10 minutes or until tender. Drain the potatoes and leave to steam dry.

Heat vegetable oil in a sauté pan over medium heat. Add cumin and black mustard seeds, cooking for about a minute until fragrant.

Add sliced onions to the pan and cook over medium heat for about 15 minutes, stirring occasionally until soft and caramelized.

Add grated garlic, ginger, and diced chilli, cooking for another 2 minutes. Then sprinkle in ground cumin, coriander, turmeric, chilli powder, and garam masala. Stir in frozen peas and continue cooking for 5 minutes.

Add cooked potatoes and lime pickle to the pan, stirring gently to coat. Finish with chopped fresh coriander and season with salt. Set aside to cool.

Beat the egg in a small bowl. Unroll puff pastry on a clean surface and place the filling in a line slightly off-center.

Cut diagonal incisions on the longer edge of the pastry. Brush the opposite side with beaten egg and fold over the filling, pressing edges to seal.

Brush the outside of the rolls with egg wash and refrigerate for 20 minutes.

Preheat your oven to 190°C (375°F). Cut the rolls into four equal lengths and place them on a baking sheet. Bake for 15-20 minutes until puffed and golden brown.