1. Prepare a grill for medium heat, about 350°F.
2. Prepare the pork loin filet by slicing it in half.
3. Oil your grill grates with a high-temperature cooking oil.
4. Grill the pork loin on direct heat until it reaches 145°F internal temperature. Remove the pork loin and let it rest under foil.
5. Grill the onion “rings” until char marks have formed on both sides. Remove and let cool.
6. Slice the pork thinly into bite-sized pieces, and then chop the grilled onions.
7. Layer two flatbreads on top of each other making two pizzas. Layer goat cheese crumbles, onion, and pork on the pizzas. Drizzle with balsamic glaze. Place on grill and let them bake until the cheese begins to melt, and the flatbreads begin to brown and get crispy and firm, approximately 8-10 minutes.
8. Remove from the grill and place on a cutting board. Layer arugula onto each pizza and drizzle balsamic glaze over the pizzas.