Sourdough starter brings flavor and nutrition to otherwise lifeless baked goods. It also carries on a tradition of baking which is so central to many cuisines throughout history: fermenting grains ...
Peel, halve and core the apples and slice them crosswise 1/4 inch thick. Set aside the larger center slices and coarsely chop the end slices and any broken ones; about half of the slices should be chopped. In a small bowl, whisk the lemon zest, juice, flour and vanilla. Toss the apples lightly in mixture.
Preheat the oven to 400°. Line a rimmed baking sheet with parchment or a silpat. On a lightly floured work surface, roll out the pastry to a 10-12 inch circle, leaving it slightly thicker in the center. Transfer to baking sheet. Spread the caramel sauce in the center of the dough leaving a 3 inch border. Spread the chopped apples over the pastry to within 1 inch of the edge. Decoratively arrange the apple slices on top in concentric circles or in slightly overlapping rows. Sprinkle the sugar evenly over the apples and dot with the pieces of butter. Sprinkle with pecan halves. Fold the pastry edge up and over the apples to create a 1-inch border.
Bake the galette for about 45 minutes or until the pastry is browned and crisp and all of the apples are tender. Transfer the pan to a rack and let the galette cool. Serve warm or at room temperature.