Place the Oreos in a food processor and blitz until finely chopped. Alternatively, place them in a sealable freezer bag wrapped in a tea towel and bash them with a rolling pin.
Tip the crumbs into a bowl and stir in the melted vegan butter. The mixture should resemble wet sand.
Tip the Oreo mixture into a 23-25cm/9-10in loose bottomed tart tin and press it across the base and most of the way up the sides. Use the base of a glass to pack it down really firmly. Place in the fridge for half an hour to firm up.
Place the chopped chocolate in a heat proof bowl. Heat the coconut milk, stem ginger syrup and vanilla extract until just boiling then pour it over the chocolate. Set aside for two minutes then stir gently until it is melted and smooth.
Scatter the chopped stem ginger over the Oreo base then pour over the ganache. Pop the tart in the fridge for around 4 hours (or overnight) until firm.
Shortly before serving, decorate the tart with fresh fruit and chopped crystallised or stem ginger. Keep refrigerated.