MAKE LAMB:
In a small bowl combine 3 Tbsp. oil, the zest , juice and garlic. In another bowl combine 2 Tbsp. salt, the mustard powder, pepper, celery seed, nutmeg and allspice.
Preheat the oven to 375*F.
Place one rack in center and one rack on lowest level. Rinse lamb and pat dry.
Place, fat side up in a large roasting pan.
Using a sharp knife, make 15 to 20 slits around the lamb.
Generously rub lemon mixture over entire surface of lamb.
Follow with the spice mixture, pushing into slits.
roast lamb in the center of oven until an instant-read thermometer inserted into thickest part (without touching the bone) reads 130*F. for medium rare, about 1 hour and 45 minutes.
Meanwhile on a rimmed baking sheet, toss together fennel, lemons, remaining 2 Tbsp. oil and 1/2 tsp. salt.
After 1 hour of roasting lamb, place fennel and lemons on sheet on lower rack. Roast turning once until fennel is tender and golden, about 40 minutes.
Loosely tent lamb with foil, let stand 15 minutes before carving.
Transfer to a platter, arrange fennel and lemons around the lamb.
MAKE CHUTNEY:
Meanwhile in a medium sauce pan, melt butter over median high heat.
Add onion and cook stirring until softened about 4 minutes. Stir in apples, sugar, raisins, vinegar, salt, nutmeg and 1/3 cup water.
Bring to a boil, reduce heat to medium and apples are tender and mixture has thickened slightly, about 8 minutes.
Remove from heat and stir in mint..
Serve with lamb.
