1. Combine white wine, sugar, water and vanilla pod, split in half lengthways in a large saucepan. Bring to the boil, stirring until sugar dissolves. Turn down heat, add peeled firm pears and cook gently to poach pears until just tender - this will take 10 to 15 minutes. Remove from heat and transfer to a bowl so pears cool in syrup. Refrigerate to chill well. Serve drizzled with chocolate sauce.
2. To make the sauce, put dark chocolate, coarsely chopped and water in a heatproof bowl and melt together, either in a microwave or over a saucepan of simmering water. Whisk until smooth. Serve warm, drizzled over pears.

Tip: Store chocolate away from heat and moisture, which can cause white streaks or powdery blotches known as "bloom" to appear. This doesn't affect the flavour but is best avoided by storing chocolate in a cool, dry place.