Put the ground pork, grated onion, parsley, dried mint, salt, and pepper in a large mixing bowl. Mix with your hands for 2 to 3 minutes until the mixture feels sticky and holds together.
Cover the bowl and chill in the fridge for 30 minutes. This firms up the meat so it's easier to shape and less likely to fall apart on the grill.
While the meat chills, rinse the caul fat under cold water and soak it in a bowl of cold water for 10 minutes to soften. Cut it into 12 squares, about 15 x 15 cm / 6 x 6 inch each.
Divide the meat mixture into 12 portions, about 80 g each. Shape each portion into a log about 10 cm / 4 inch long.
Lay one meat log on a caul fat square. Wrap the fat around the meat, tucking the ends underneath so the log is fully covered. Repeat with the remaining logs.
Heat a charcoal grill or a 30 cm / 12-inch ridged grill pan over medium-high heat, about 200 C / 400 F.
Place the sheftalia on the grill, seam side down first. Grill for 15 to 18 minutes total, turning every 3 to 4 minutes, until the caul fat is crisp and deep golden and an instant-read thermometer reads 160 F / 71 C in the center.
If the fat starts to flare up from dripping onto the coals, move the sheftalia to a cooler part of the grill for a minute before continuing.
Move the sheftalia to a plate and let them rest for 5 minutes before serving.
Serve warm with warm pita, lemon wedges, and a simple tomato and cucumber salad.