Slice the meat as thin as possible. Use a mallet to tenderize and soften the meat, making them very thin.
In a bowl combine the seed oil, olive oil, mustard, vinegar, cumin, salt, paprika, chili flakes, pepper, honey, garlic, onion, and oregano.
Add the meat to the bowl with the marinade and mix well. Cover with plastic wrap and refrigerate for at least 1 hour, up to 12 hours.
Make Tzatziki by coarsely grating the cucumber, then straining in the sink. Squeeze as much liquid out as possible. Then press cucumber between towels.
Combine garlic, lemon zest, lemon juice, salt and any herbs into the yogurt and mix well. Add salt as needed and refrigerate at least 30 minutes. (You can keep this refrigerated for up to a week in a sealed container.)
Preheat grill to high or oven to 450 degrees.
Thread a slice piece of meat onto a skewer: start by piercing through it twice on one end, then push it together like an accordion. Continue piercing and threading, making the meat tightly bunched together (no part of the skewer should be exposed except for handle at the bottom and the pointy top.) Repeat until all meat is threaded onto skewers.
On a grill: grill over high heat for about 4 minutes per side until charred/caramelized on all sides or pork is cooked all the way through (155 degrees).
In an oven: place skewers on lined baking sheet in upper part of oven and roast for 10-15 minutes, turning occasionally to get the skewers evenly browned.
Let the meat rest for a few minutes, then remove from skewers and chop into bite size pieces. Serve on top of warm pita with tzatziki, sliced tomatoes and red onion.