For the Filling:
20 ounces fresh peaches, peeled, pitted and cut into 1/8-inch slices
1/3 cup brown sugar
1 tablespoon all-purpose flour
1/3 cup chopped pecans
1 teaspoon vanilla extract
¼ teaspoon ground cinnamon
For the Strudel Assembly:
5 sheets phyllo dough, thawed (use 14x18-inch phyllo for 1 large strudel; use 9x14-inch phyllo for 2 small strudels)
5 tablespoons unsalted butter, melted
2 tablespoons granulated sugar
1. Adjust oven rack to lower-middle position and preheat oven to 450 degrees F. Line a baking sheet with parchment paper; set aside.
2. Stir together the peaches, brown sugar, flour, pecans, vanilla extract and cinnamon; set aside.
3. Place a silicone mat or a piece of parchment on your work surface. Place a sheet of phyllo on the mat or parchment, with the long side facing you. Brush the sheet of phyllo with melted butter and sprinkle with 1 teaspoon of the sugar. Repeat with the remaining four sheets of phyllo, stacking them on top of one another.
4. Place the filling in a 3-inch-wide strip about 2½ inches from the bottom and 2 inches from each side of the phyllo (if you are using the smaller size phyllo, use half of the filling and repeat the steps with additional phyllo). Fold the short sides of phyllo over the filling. Then fold the bottom of the phyllo over the filling and very gently roll the strudel loosely.
5. Place the strudel, steam-side down, on the baking sheet. Brush with the melted butter and sprinkle with sugar. Cut four 1-inch-long vents in the top of the strudel. Bake until golden brown, 15 to 20 minutes. Place the baking sheet on a cooling rack and allow to cool until warm, about 30 minutes.