1. In a large bowl, combine the ground beef, grated onion, barbecue sauce, panko crumbs, soy milk, egg, salt, and pepper. Mix well.
2. Shape into 18 four-inch (2 and 1/2-centimeter) round patties.
3. Place one teaspoon chicken pastrami filling in the center.
4. Fold all edges over the filling and form into a patty. You may freeze the patties at this point.