Preheat oven to 375 degrees F. Coat a baking sheet with cooking spray.

Combine strawberries, rhubarb, 2 tablespoons sugar, flour, tapioca, cinnamon and salt in a medium bowl.

Unroll phyllo sheets onto a clean, dry surface, keeping them in a stack. Cover with a sheet of wax paper and then a damp kitchen towel. (Keep the phyllo covered to prevent it from drying out while you work.) Take one sheet of phyllo from the stack and place it on another clean, dry surface with a short side closest to you. Starting at the center and working toward the edges, lightly brush the sheet with oil. Lay another sheet of phyllo on top and brush with oil; repeat with the remaining sheets of phyllo.

Mound the strawberry-rhubarb filling on the lower third of the phyllo stack, leaving a 2-inch border at the bottom and sides. Fold the long edges in toward the center and, starting at the short edge nearest you, roll the filling and phyllo into a cylinder. Roll up firmly but not too tightly, to allow a little room for expansion.

Brush the strudel with oil and sprinkle with the remaining 1/2 teaspoon sugar. Carefully transfer the strudel to the prepared baking sheet, placing it seam-side down. Poke several steam vents in the top using the tip of a sharp knife.

Bake the strudel until golden brown, 30 to 35 minutes. Cool on the pan for 10 minutes before serving.

Tip for Two: The 9-by-14-inch pieces of phyllo (or fillo or filo) dough are just the right size when making desserts for two, but phyllo comes in a variety of sizes. Trim larger sheets to approximately the right size. Leftovers: Each box of phyllo has more sheets than you'll need for a small dessert. Store defrosted phyllo in the refrigerator or freezer. Simply remove the sheets you need, reroll the rest, wrap tightly in plastic and refrigerate for up to 1 month or freeze up to 9 months.