Vidalia Onion Tart

1 Tbsp. margarine, preferably unsalted
2 tsp. sugar
6-8 small Vidalia onions, peeled and cut in half crosswise
1 Tbsp. fresh thyme, plus more for garnish
Salt and freshly ground black pepper, to taste
1 1/2 cups faux chicken broth (try Osem or Telma brands, available in the kosher section of supermarkets)
1 tsp. balsamic vinegar
1 sheet frozen puff pastry dough, thawed (try Pepperidge Farm)

• Melt the margarine in a medium ovenproof skillet. Remove it from the heat and sprinkle it with the sugar. Fit the onions snugly into the skillet, cut sides facing down. Sprinkle them with the thyme, salt, and pepper. Return the skillet to the stove and cook over medium heat for 10 minutes until the onions are deep golden brown on the cut sides.
• Mix the broth and vinegar together and pour over the onions. Bring the dish to a simmer, cover, and cook over low heat for 25 minutes. Remove the lid, raise the heat, and cook until the liquid is syrupy and almost completely reduced. Remove the skillet from the heat.
• Preheat the oven to 375°F.
• Roll out the puff pastry until it is slightly larger than the skillet, then trim it into a round shape. Place the dough over the pan, tucking in the edges and poking a few holes in the top. Place the pan in the oven and bake until the pastry is puffed and golden (about 30 minutes). Remove it from the oven and allow it cool for 10 minutes. Invert the tart onto a serving plate. Serve warm, garnished with fresh thyme.

Makes 8 servings