Preheat your oven to 500°F (260°C) and place a pizza stone inside if using.
In a skillet over medium-low heat, add olive oil and sliced onions. Stir occasionally and cook for 15–20 minutes until deeply golden. Add balsamic vinegar and a pinch of salt in the last few minutes.
Assembly:
On a lightly floured surface, stretch or roll the pizza dough into a 10–12 inch round.
Transfer the dough to a floured pizza peel or parchment paper.