Combine lemon juice, garlic, salt, mustard, chili powder, cumin, thyme and pepper.
Pour over lamb in large shallow dish or pan.
Marinate several hours or overnight.
Place spareribs on rack in shallow roasting pan; reserve marinade.
Roast lamb 1 hour and 30 minutes, basting occasionally with marinade.
Sprinkle with paprika; roast 30 minutes longer or until tender.
Garnish with thickly sliced tomatoes and parsley.
To barbecue lamb, arrange on skewers; sprinkle with paprika.
Grill 6 to 7 inches from heat 30 minutes per side or to desireddoneness, basting occasionally with marinade.