In a mixing bowl, combine the minced garlic, olive oil, rosemary, thyme, salt, and black pepper.
Place the lamb leg steaks in a zip-top plastic bag and pour in the marinade. Close the bag and knead the marinade into the steaks. Chill in the refrigerator for a minimum of 1 hour, or even better, overnight.
Over medium-high heat, preheat your grill or stovetop pan.
Remove the steaks from the marinade and let any excess drip off.
Place the steaks on the grill or pan and cook for about 4-5 minutes on each side for medium-rare. Use a meat thermometer to ensure the internal temperature reaches 145°F (63°C).
Once cooked to your desired doneness, remove the steaks from the heat and let them rest for a few minutes before slicing.
Serve the lamb leg steak slices with your choice of sides.