Bring a small pan of water to a rolling boil, drop in the potatoes and cook for 12 minutes, or until tender. Drain and leave to dry in the colander.

When dry, put the cooked potatoes back into the same pan, add the oil, half a teaspoon of salt and the nigella seeds, and mash really well. Add the flour and knead with your hands until the mix comes together into a uniform ball of dough.

Lightly flour a work surface and lay out a large sheet of greaseproof paper. Cut the roti dough into four equal pieces. Take one piece of dough, roll it out into a 6cm-diameter circle (dip the rolling pin in flour if need be), then transfer to the paper and repeat with the remaining dough.

Heat a teaspoon of oil in a large, nonstick frying pan and, when hot, lay in the rotis and cook for about a minute and a half on each side, until blackened in places and there are no uncooked, doughy spots – as the pan starts to heat up, the roti will cook more quickly, so you may need to reduce the cooking time and/or heat.

Cover the cooked rotis with foil and set aside while you make the kheema. In the same frying pan, heat the oil for the kheema over a medium heat.

When hot, add the leek and onion, and cook for about eight minutes, until soft and translucent. Add the ginger, garlic and chillies, stir to mix and cook for two minutes more.

Crumble in the haggis and cook, stirring frequently, for about eight minutes – it may stick to the pan, but persevere.

Stir in the ground coriander, cumin, turmeric and yoghurt, cook for a further four minutes, then taste for seasoning. Add salt a quarter-teaspoon at a time, mixing and tasting after each addition, then stir in the fresh herbs and serve hot with the rotis.