1. crust: blitz the cookies, espresso powder and salt in a food processor to a crumb consistency. add the butter and blend until the mixture sticks. press the mixture into a 9.5” (24cm) pie dish or tart tin. smooth it out with the back of a spoon and place in the freezer while you make the caramel. 2. Caramel: add the sugar, condensed milk and vinegar to a pot. dissolve slowly over a low heat over 2-3 minutes, using a rubber spatula to stir it every so often. 3. Increase to heat to medium until the caramel comes to a simmer, cook for 8-10 minutes, until it turns amber in colour. do not whisk during this process. 4. Remove from the heat and slowly add the chunks of butter to the caramel a few at a time, stirring between each one to combine. stir in the espresso in 2-3 increments and mix in well, add in the salt. 5. Cool the caramel for 10 minutes then pour it into the pie. place in the fridge. 6. Mousse: add all the ingredients to a blender until smooth. pour into the tart, smooth out the top and chill for 6 hours (or overnight). garnish with vegan whipped cream or meringue and chocolate curls before serving!