Prepare mussels (see tip in PDF). Mix sugar, honey and 2 tablespoons of water in a pot. Caramelise over a low to medium heat for approx. 8 minutes until golden, stirring frequently. Remove the pot from the stove.
Stir in butter and 1 pinch of salt. Pour the caramel into the mussels quickly (if the caramel becomes firm in between, reheat it at low heat). Sprinkle with a little salt (if you don't like the salty part, just leave it out).
Let it cool down. The mussels can be kept refrigerated for about 2 weeks.