Grate the cucumber on the coarse side of a box grater, then wrap it in a clean kitchen towel and squeeze firmly until almost no liquid comes out.

Combine the squeezed cucumber, Greek yogurt, minced garlic, dill, lemon juice, olive oil, and salt in a medium bowl. Stir well until uniform.

Taste and adjust salt. Cover and refrigerate until ready to serve - at least 10 minutes so the flavors settle.

Place the ground beef in a large mixing bowl. Add grated onion, minced garlic, parsley, cumin, coriander, smoked paprika, cinnamon, cayenne, salt, and black pepper.

Mix firmly with your hands for about 90 seconds until the spices are evenly distributed and the mixture is slightly sticky. Do not overwork it.

Divide the mixture into 8 to 10 equal portions (about 70 g each). Press each portion firmly around a flat skewer, shaping it into a log roughly 12 cm long and 3 cm wide.

Place shaped koftas on a lined tray and refrigerate for 20 minutes. This step keeps them stable during cooking.

Heat a ridged cast-iron grill pan over high heat for 3 minutes until smoking. Alternatively, preheat an outdoor grill to high.

Lightly brush the koftas with olive oil. Place on the grill pan without crowding - cook in two batches if needed.

Cook for 4 to 5 minutes on the first side without moving, until deep brown grill marks form and the koftas release cleanly from the surface.

Turn and cook for another 4 to 5 minutes on the second side until the koftas are cooked through. An instant-read thermometer should read 71 C / 160 F at the center.

Transfer to a warm plate and rest for 3 minutes before serving.

Arrange 2 to 3 kofta skewers per plate alongside a generous spoonful of tzatziki. Serve with warm flatbreads, sliced tomatoes, and fresh parsley if desired.