Cooking time: 1 hour 45 minutes
Place elderflower concentrate in a medium heavy-based saucepan and bring to boil over a medium heat. Simmer for 12 minutes or until reduced by half. Add rhubarb, caster sugar, maltose, vinegar, ginger and star anise, and cook, stirring occasionally, for 25 minutes or until syrupy. Cool. Remove and discard star anise. Place rhubarb mixture in a blender and blend until smooth.
Preheat oven to 180°C. Using a small sharp knife, cut around shank of ham in a zigzag pattern, about 10cm from end. Carefully run knife under rind around edge of ham. Gently lift off rind in one piece by running your fingers between rind and fat. Trim excess fat from ham, leaving a 1cm-thick covering. Using a small sharp knife, score fat in a diamond pattern, about 5mm deep, taking care not to cut into meat. Cover hock with foil to prevent burning.
Place ham on a lightly greased wire rack in prepared pan. Brush ham with rhubarb glaze. Bake, basting with glaze every 20 minutes, for 1 hour or until ham is golden and caramelised.
Recipe by Tasmanian chef Steve Cumper, from homestolove.com.au