Preheat oven to 400 degrees.

In a small bowl, whisk together Sriracha, honey, soy sauce, lime juice, melted butter, and salt until combined. Set aside.

Line a rimmed baking sheet with aluminum foil. Add the halved Brussels sprouts and drizzle 1/4 cup of the honey Sriracha sauce. Use your hands to make sure all the Brussels sprouts are coated with the sauce. Roast in the oven for 20 minutes. Remove from oven and set aside.

While the Brussels sprouts are roasting, heat the sliced onion in a dry small skillet over medium-high heat. Once browned, add approximately 2 to 3 Tbsp of water to the pan and continue to cook until caramelized. Remove from heat and sprinkle with a pinch of salt and pepper.

Roll out the pizza dough to a 18x13 inch rectangle. Add it to a baking sheet or pizza stone and prick all over with a fork. Place in the oven and bake for approximately 15 minutes, until golden brown and cooked through.

Sprinkle the dough with grated fontina and return to the oven for approximately 5 minutes, until the cheese is melted and bubbly. Top with Brussels sprouts, crisp pancetta, and caramelized onions. Drizzle with additional sauce. Serve immediately.