In a bowl, combine the olive oil, herbs (oregano, basil, mint), minced garlic, crushed red pepper flakes, sea salt, minced red onion, and lemon juice and zest.
Add the lamb to the mixture and marinate for at least 30 minutes, or preferably overnight, in the refrigerator.
Heat a cast iron skillet over high heat.
Add the marinated lamb to the hot skillet and cook for 10 minutes, or until a char is formed and the lamb is cooked through.
Remove the lamb from the heat.
Warm the corn tortillas. Fill each tortilla with the cooked lamb.
Top with a squeeze of fresh lime juice, minced red onion, and minced cilantro. Serve immediately.