Preheat your oven to 450°F (230°C).
Prepare the lamb by trimming excess fat if necessary.
In a small bowl, combine minced garlic, chopped rosemary, thyme, olive oil, salt, and pepper to create a marinade.
Rub the marinade all over the leg of lamb, ensuring it's evenly coated.
Place the lamb in a roasting pan and insert a meat thermometer into the thickest part without touching the bone.
Roast in the preheated oven for 20 minutes to develop a crust.
Reduce the oven temperature to 325°F (160°C) and continue roasting for 1.5 to 2 hours, or until the thermometer reads 135°F (57°C) for medium-rare.
Remove the lamb from the oven and let it rest for at least 15-20 minutes before carving.
While the lamb rests, prepare the mint chimichurri by combining mint, parsley, red wine vinegar, red pepper flakes, and salt in a bowl.
Carve the lamb into slices and serve it with a generous spoonful of mint chimichurri on top.
