To make the pastry, sift the flour into a large bowl along with a pinch of salt. Rub in the soya spread until the mixture resembles breadcrumbs. Add 2 tbsp ice-cold water and bring together with a knife.
Turn out on to a lightly floured surface and bring together with your hands. Wrap the pastry in clingfilm and chill in the fridge for 30 minutes. Grease a 22cm fluted tart tin and preheat the oven to 200°C/gas mark 6.
To make the filling, heat 1 tbsp of the oil in a large lidded frying pan. Cook the onion for 3-4 minutes until beginning to soften, the add the garlic and cook for 1 minute. Cube the butternut, then add to the pan with the sage, seasoning and a splash of water. Cover and cook for 10-12 minutes or until tender, checking occasionally so it doesn’t stick. Remove once cooked and mash thoroughly in a bowl.
Trim the ends of the courgettes, carrot and aubergines. Then, using either a mandolin or vegetable peeler, slice lengthways into long thin ribbons. Whisk 2 tbsp olive oil with the agave and chilli or paprika flakes, then toss with the veg strips in a bowl.
Roll the chilled pastry out on to a lightly floured surface to about ½cm thick. Fill the pie dish with the pastry and trim any overhanging edges, then prick the base with a fork. Lay a circle of foil or baking paper on the base and cover with baking beans. Bake in the oven for 10 minutes, then remove the beans and bake for another 5 minutes.
Remove the tart shell from the oven and turn down to 180°C/gas mark 4. Spread the base with the butternut puree. Take a ribbon each of carrot, aubergine and courgette, and roll together into a tight spiral. Place in the middle of your tart, then use the rest of the veg ribbons to form concentric circles around to fill the shell. You might need to trim some of the ribbons to size. Brush all over with the remaining 1 tbsp olive oil, then put back in the oven and bake for 40-45 mins until the veg is cooked through. Slice into wedges to serve.