To make the marinade: In a large glass bowl, whisk together the olive oil, lemon juice
, orange juice, chili flakes, chili powder
, garlic, salt, and black pepper. Add in the pork
and toss to coat. Cover the bowl and refrigerate for at least 30 minutes (although I prefer to marinate for 3 hours or overnight).
Soak the wooden skewers in a shallow pan of water for at least 1 hour.
Remove the pork cubes from the marinade. Thread 3 or 4 pieces of marinated pork on the skewers, alternating the pork with small wedges of lemons
and oranges. Place the skewers on an area of the grill
with no direct flame. Continue to brush marinade
during grilling, until the meat is browned, about 8 to 10 minutes, turning occasionally or to desired doneness. Transfer the pork from the skewers and place in pita pockets. Top the pork with shredded lettuce and avocado tzatziki.