1. Preheat pizza stone on the grill (or in oven). Unroll the refrigerated Classic Pizza dough with parchment paper and cut dough into 8 equal-sized triangles. For an extra crispy crust, you can heat up a pizza stone on the grill or use it in the oven (oven temperature 425°F regular oven) and bake pizza triangles on stone without parchment paper.
2. To make homemade Pepperonata: Peel onions, cut in half lengthwise, and cut crosswise into fine strips. Peel garlic clove and chop finely. Clean red and yellow bell pepper, rinse, cut into quarters lengthwise, remove seeds and stems, and cut crosswise into strips. In a saucepan, heat olive oil. Add onions and garlic and braise for 3-4 minutes while stirring. Stir in bell pepper strips and braise for another 3-4 minutes. Add coarsely diced tomatoes, vegetable stock, and balsamic vinegar. Season with salt, cayenne pepper, and 1-2 pinches sugar and simmer over low heat for 6-8 minutes.
3. Distribute Peperonata evenly over the triangles, leaving a small margin around the edges. Sprinkle each triangle with 1 Tbsp. grated Parmesan.
4. Place Pizza Triangles without the parchment paper on the hot pizza stone, cook on the grill until golden-brown, and serve immediately. Baking time on grill and in oven differ, best check on baking progress every 1-2 minutes when cooking on a grill.