Fig and Caramelized Onion Tart

Name: Fig and Caramelized Onion Tart
Ingredients: 2 tablespoons extra-virgin olive oil; 1 large yellow onion, peeled and thinly sliced; 1 shallot bulb, peeled and thinly sliced; 1/2 teaspoon kosher salt; 1 tablespoon good-quality Balsamic vinegar; 1 puff pastry, defrosted (I use Dufour); 1/2 pound fresh figs, washed, trimmed and sliced into fourths; 3 slices bacon, fried, drained on paper towels and crumbled; 3 ounces Valdeon (or a similar blue cheese), crumbled; freshly ground black pepper