Combine ingredients for marinade and pour half of it over the lamb leg steaks. Turn lamb in marinade to coat evenly. Marinate for 10-30 minutes, until you're ready to cook. Keep reserved marinade to serve.
Preheat a grill pan or BBQ to very hot. Cook corn for 10 minutes, turning to char evenly. Cook asparagus for 2-3 minutes and tomatoes for 1-2 minutes.
Cook lamb on grill pan or BBQ for 2-2.5 minutes per side for medium. Rest for 5-10 minutes, then slice to serve. Serve with vegetables and reserved marinade.
Try fresh red or green chillies instead of jalapenos
Marinate the lamb the night before for greater flavour.
Add a little of the reserved marinade to the vegetables before or after cooking to give them a bit of a kick.