Heat the oven to 200C/180C fan/gas 6. Tip the squash and onions into a large roasting tin with 1 tbsp olive oil, most of the cumin seeds, 2 tbsp harissa and some seasoning. Roast for 35-40 mins, tossing once or twice until the veg is soft and charred in spots. Leave to cool slightly, then roughly mash together using a potato masher – you want to retain some chunks of squash. Stir through the feta and season with salt, if needed. The veg can be roasted a day ahead and kept chilled.

To assemble, unravel the filo pastry. Brush one sheet liberally with some of the remaining oil, and keep the rest covered with a damp tea towel to stop it drying out. Drape the oiled sheet, oiled-side down, into a 22cm loose-bottomed cake tin so that some of the pastry hangs over the side. Repeat with another sheet of pastry, turning it by about 45 degrees over the first sheet in the tin, then again with the last two pastry sheets.

Spoon in the filling, then pull the overhanging pastry up and towards the centre, scrunching it to enclose the filling. Scatter with the remaining cumin seeds and brush with a little more oil.

Reduce the oven temperature to 190C/170C fan/gas 5. Bake the pie for 30 mins until the pastry is crisp and golden brown. Meanwhile, mix the tahini with the remaining harissa, the lemon juice and 4 tbsp water, then season to taste. Remove the pie to a serving plate, slice into wedges and serve with sauce for drizzling over. Or, cool to room temperature first.