Preheat the oven to 400°F / 200°C (Gas Mark 6 / 180°C fan-forced).

Lightly grease the pie dish with dairy-free margarine or cooking spray.

Make the pastry first: Mix the gram flour, sorghum flour and tapioca starch, rub in the margarine until the mixture resembles breadcrumbs, then add the cold water and bring together to form a dough. Wrap in a large piece of cling film and put it in the fridge.

Chop the onion, carrots and sweet potato into small chunks and dry fry for 5-10 minutes. Add the mince and continue to fry until it has browned.

Add the nutritional yeast and marmite and stir into the mixture before adding the ⅔ cup (160ml) of water.

Simmer for 20-30 minutes (occasionally stirring, so it doesn't stick) until the vegetables are softened and most water has been absorbed into the mixture.

Whilst the vegetables and meat are cooking, roll out the pastry: Take two thirds and put the other third back in the fridge.

IMPORTANT NOTE: gluten-free pastry is very 'short', which means it will easily crumble. The best and easiest way to handle it is to roll out between a folded over sheet of cling film so it doesn't stick to either the work surface or the rolling pin.

Flatten your large piece of cling film on your work surface and put the dough roughly in the middle, folding the other half over the top of the dough. Now roll out, occasionally measuring against your pie dish. When big enough, peel back the top side of the cling film and lift the rolled out pastry, carefully inverting it into the greased pie dish. Once placed in the dish, peel back the bottom layer of cling film, and you can cut away any of the sides if they are too long.

Don't worry if your pastry doesn't quite fit. Use your fingers to stretch it out and add extra pieces if it's too short. It doesn't need to be perfect.

Once the mince and vegetables are cooked, and water has been mostly absorbed into the mixture, add it to the pastry case.

Roll out the rest of the pastry in the cling film like before and place it on top of the mince and vegetable mixture to close your pie. Use your thumbs to press the lid of the pastry together with the edges of the case. Pierce with a fork several times and brush with a little dairy-free milk.

Place the pie in the centre of the oven and bake for 30 minutes until the pastry is golden brown all over. If the edges are browning too quickly, loosely cover with foil for the final 10 minutes. Allow the pie to rest for 10 minutes before slicing — this lets the filling set and makes for cleaner slices.