Put the sweet potato chunks into a large saucepan and pour over enough boiling water to cover, bring back to the boil and then simmer for 15 minutes until the sweet potato is tender. Drain and mash with a little salt and pepper.

While the sweet potato is cooking, put the oil in a wide, shallow grill proof pan (I used a cast iron sauté pan) and add the onions, fry on a low heat with the lid on for 3 minutes until softened.

Remove the lid and turn up the heat. Add the lamb mince and brown for 3 minutes, then turn the heat back down again and add the garlic, ginger, chilli, cumin, turmeric and garam masala, cook for a further 4 minutes, stirring occasionally.

Add the chopped tomatoes and bring to the boil, then turn down and simmer for 10 minutes. Turn your grill on to medium-high to heat up.

Remove the mince from the heat and spread the mashed sweet potato over the top – place under the pre-heated grill for 10 minutes until nicely browned on top. If your grill is a bit uneven, the pie might need to be turned around after 5 minutes to ensure even browning.

While the shepherd’s pie is under the grill, quickly cook your peas (or whatever vegetable you are having to accompany your shepherd’s pie).

When the pie is nicely browned on top, serve with the veggies and any pickles or chutneys you like.