Method
1. Fill and boil your kettle. Fill a large pan with the hot water and place on a medium heat. Add a pinch of salt, cover and bring back to the boil.
2. Peel and chop the sweet potatoes, then add them to the pan and simmer for 15–20 mins, till tender.
3. Meanwhile, refill and boil the kettle. Rinse the porcini mushrooms under cold water and squeeze out any excess water, then tip them into a heatproof jug. Crumble in the stock cube and add the tamari and tomato ketchup. Pour in 1 ltr hot water, stir well, then pop to one side.
4. Trim the roots and woody greens off the leeks, and rinse out any grit. Halve lengthways, then thinly slice. Peel and finely chop the carrot. Tear or chop the chestnut mushrooms into small pieces. Peel and thinly slice the garlic cloves. Pick the thyme leaves off their woody stems and roughly chop them.
5. Drizzle 2 tbsp oil into a large pan and warm over a medium heat. Slide the chopped leeks, carrot, mushrooms, garlic and thyme into the pan and season with a good pinch of salt and pepper. Pop a lid on the pan (or use a baking tray if you don’t have one) and fry for 10 mins, stirring occasionally, till soft and juicy.
6. Preheat the oven to 190°C/Fan 170°C/Gas 5. Tip the soya mince into the pan and pour in the tomatoey stock. Stir well to combine, then bring to the boil. Reduce to a gentle simmer, cover the pan with a lid and cook for 10 mins, stirring occasionally, till the sauce has thickened. Taste and add a pinch more salt and pepper, if you think it needs it.
7. Drain the sweet potatoes, then tip them back into the pan. Add 2 tbsp olive oil or vegan spread, if using. Season with a good pinch of salt and pepper, then crush with a potato masher or fork.
8. Transfer the filling to a large ovenproof dish, and top with the sweet potato mash. Slide into the oven and bake for 25–30 mins till browned and bubbling. Divide between plates and serve.
9. Love Your Leftovers
The pie will keep well in the fridge for up to 3 days, stored in an airtight tub. Divide the mash and filling between the tubs, seal and store. This is best reheated in the microwave till piping hot.
10. Energy Saver
When you’re frying veggies to start making a sauce, soup or stew, popping a lid on the pan helps to keep the heat and steam in the pan, speeding up the cook time and saving energy. If you don’t have a lid, use a baking tray to cover the pan or a circle of greaseproof paper laid over the top of the veggies. Remove occasionally to stir the veg.