Place sugar in a medium saucepan over low heat. Shake pan to spread sugar. Leave for a few minutes until the edges start melting and turning golden, then swirl the pan to spread the caramel/sugar to encourage even melting (do not stir, sugar may crystallise).

Once the sugar is all melted, add apple and vinegar. Mix, and cook for 8 - 10 minutes, stirring occasionally, until the apple is completely soft.

Add the butter, stir it in until mostly melted. Blitz until smooth using a stick blender (tilt saucepan if needed to ensure head is completely submerged to avoid splattering).

Serve with: Slow-roasted crispy pork belly or any pork dishes. Also great for sweet applications – see in post for more ideas!