In a bowl, combine the pork cubes, olive oil, minced garlic, dried oregano, salt and pepper. Marinate for at least 2 hours, or preferably overnight in the refrigerator.
Preheat your grill to medium-high heat 20 minutes prior to cooking. Adjust top and bottom vents until the grill settles near 450F.
Thread the marinated pork cubes onto skewers, leaving a small gap between each piece. This allows for even cooking and ensures a beautiful char on the outside.
Place the pork skewers on the preheated grill and cook for about 10-12 minutes, turning occasionally, until the pork is cooked through and nicely charred on the outside.
While the pork is grilling, prepare the tzatziki. In a bowl, combine the Greek yogurt, grated cucumber, minced garlic, olive oil, lemon juice, chopped dill, salt, and pepper. Stir well to combine and refrigerate until ready to serve.
Lightly brush the pita bread rounds with olive oil and place them on the grill for about 1-2 minutes on each side, until they are warm and have nice grill marks.
Once the pork is cooked, remove it from the grill and let it rest for a few minutes. Then, carefully slide the pork cubes off the skewers.
Serve the grilled pork neck souvlaki with the grilled pita bread and a generous dollop of homemade tzatziki. Garnish with tomato, pickled onion, feta, and additional fresh dill.