Gently mix turkey, pancetta, onion, and bread crumbs in a large bowl; season with 1 teaspoon salt and a pinch of pepper. Stir in the egg, sage, and zest. Form mixture into 1-inch meatballs

Heat 1 to 2 tablespoons oil in a large heavy skillet over medium- high until hot but not smoking. Cook the meatballs in a single layer ( work in two batches, if necessary), turning as needed, until browned on all sides and cooked through, about 7 minutes. Transfer to a plate and tent with parchment paper, then foil, to keep warm.