In a bowl whisk together avocado oil, oregano, smoked paprika, cumin, and red pepper flakes. Season to taste with salt and pepper.
Add the cubed lamb and mix well.
Cover and marinate in the refrigerator for at least 2 hours or overnight.
Soak skewers in water for 30 minutes.
Preheat a grill or grill pan to medium high. Brush the grates with oil.
Remove the lamb from the marinade. Thread the lamb, onion, red pepper and olives onto the wooden skewers. Season will salt and pepper.
Grill the kebabs, turning as needed, for about 10 minutes. (Or to desired doneness.)
Serve with Tzataki over cauliflower rice.