From the night before mix in a bowl the pork, the onion, 1 tablespoon olive oil, salt, pepper, oregano, cumin, and refrigerate.
Grate cucumber, put it in a strainer, add some salt, and let it strain for 10 minutes. Squeeze firmly with your hands and add it in a bowl with the yogurt, black garlic, pepper, dill, and apple cider vinegar.
Mix well and refrigerate.
Grill them in a grill pan over high heat or over charcoals, until well browned and caramelized, about 5 minutes each side (you can also bake them in the oven with slightly tougher results). Brush them with some olive oil 1 minute before done.