Step 1Heat the oven to 400 degrees.
Step 2Combine the cherries and kirsch in a small bowl; set aside to soften the cherries.
Step 3Melt 2 tablespoons of the butter in a large nonstick skillet over medium heat. Add the quince and cook, stirring frequently, until it has softened slightly, about 10 minutes. Add the brown sugar and continue to cook until the sugar has caramelized a bit, 3 to 4 minutes.
Step 4Stir in the pecans, lemon juice and reserved cherries and kirsch. Cook until the kirsch has evaporated, another 2 to 3 minutes. Allow to come to room temperature.
Step 5While the filling cools, melt the remaining butter. Place 1 sheet of the filo on a work surface and brush with some of the butter. Repeat with the remaining sheets, layering one over another, reserving about 2 teaspoons of butter.
Step 6Spread the cooled filling evenly over the filo and roll up the strudel from the short side of the filo. Place the strudel on a baking sheet and brush with the remaining butter, then sprinkle with the coarse sugar. Bake until golden brown, about 20 minutes. Let cool about 10 minutes then slice.