Mix 5 tablespoons of the soya milk, vinegar and flaxseed together in a jug, then leave to stand for 10 minutes (the mixture will separate slightly and turn thick).
Meanwhile, heat the strawberries and sugar for the compote in a saucepan over a gentle heat for 2–3 minutes until the sugar is dissolved. Add the blackberries and cook for a further 2–3 minutes until the fruit has softened and a juice has formed. Remove from the heat and leave to cool.
Put the flour in a large bowl and stir in the caster sugar, baking powder, bicarbonate of soda and cinnamon. Add the spread and rub in with the fingertips until the mixture resembles fine breadcrumbs. Stir in the cranberries, then add the soya milk mixture and mix to form a soft dough.
Roll the dough out on a lightly floured work surface to an 18 cm (7 inch) round and score into 6 wedges with a knife. Place on a lightly greased baking sheet, brush with the remaining soya milk and sprinkle with the demerara sugar. Bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 15–18 minutes until golden and cooked through. Leave to cool slightly, then serve warm with the cooled compote.