Melt 1 tbsp Flora Cuisine in a pan, add the onion and celery and cook for about 5 minutes, stirring occasionally, until soft. Stir in the breadcrumbs, lemon rind, lemon juice, seasoning and chopped rosemary.
With a sharp knife, make several deep slashes and press in the stuffing. Weigh the joint.
Brush remaining Flora Cuisine over the lamb.
Cook in a preheated oven at 190°C, 170°C fan oven, Gas 5 for about 20 minutes per 450g (1 lb) plus 20 minutes extra. Baste the lamb several times during cooking and add the garlic for the final 30 minutes cooking.
Leave the cooked lamb to rest (covered) for about 15 minutes before carving (remember to trim off all visible fat). Serve garnished with rosemary sprigs.
For top tips on protecting you and your family when preparing raw meat and poultry, visit Food Safety in the Home and view the full Food safety at home video.