Preheat a grill to medium-high heat and preheat the oven to 425 degrees.
Line a sheet pan with parchment, then place the sweet potatoes on top and drizzle with olive oil and sprinkle with salt. Toss around, then spread into an even layer. Roast for about 15 minutes, then give the potatoes a toss. Continue roasting until browned and crisp, another 15-20 minutes or so. Season with more salt if needed.
Skewer the pork cubes onto metal or wooden skewers. If using wooden skewers, be sure to soak them for at least 30 minutes beforehand so they don’t burn up on the grill.
Grill pork until slightly charred on all sides, but be careful not to overcook. Pork can still be slightly pink in the center, and it will continue cooking after removing from the grill, so it’s better to have it be slightly underdone than over, which will cause the meat to be tough.
Allow the meat to rest for about 5 minutes before serving. While the meat is resting, warm the pitas or flatbreads in the oven for a few minutes and mix together the salad. Toss together the tomato, cucumber, red onion, and oregano, then drizzle with olive oil, lemon juice, and salt.
To serve, place a pita down on a plate, then slather with plenty of toum. Place several pieces of pork (removed from the skewer) on top, then a handful of sweet potato fries. Spoon tomato cucumber salad over, then sprinkle with crumbled feta. Fold up the pita and serve immediately.