Rinse meat, pat dry, tie off and season with salt and pepper.
Mix together oil, parsley, breadcrumbs, garlic and mustard to make a spice mixture.
Heat oil in a roasting pan and sear lamb on all sides. Rub spice mixture onto lamb. Roast in a preheated oven at 200°C (approximately 400°F) for about 2 hours, gradually adding broth to pan.
Peel and mince shallots. Melt butter in a hot pan and fry potatoes. Season with salt and pepper and add basil.
Rinse tomatoes and cut into quarters or eighths. Season with salt, pepper and shallots.
Slice lamb and serve with roasted potatoes and tomatoes.