Add mayo, garlic and lemon juice to a small mixing bowl. Stir until fully combined. Cover and refrigerate until ready to serve.
For Chicken Shwarma
Rinse and pat chicken dry with paper towel. Slice into thin strips, width-wise, and transfer to mixing bowl along with all of the spices and 2 tbsp avocado oil.
Preheat cast-iron skillet over med-high heat. Add 1 tbsp of avocado oil and the chicken. Spread meat evenly across the pan and cook undisturbed until browned (approx. 6-8min). Note: you may have to cook in batches so as not to overcrowd the pan. Flip chicken and cook additional 4-5 minutes or until fully cooked through and crispy.
Serve shwarma with a side salad, potatoes and/or cauliflower rice. Drizzle garlic sauce overtop and season everything with a dash or two of sumac.