2 cups diced (1/4 inch) butternut squash
1/2 cup finely chopped white onion
6 small garlic cloves, minced
2 tbsp olive oil
2 (2 to 3 inch) fresh jalepeño chiles, seeded and ribs discarded, finely chopped
1 pound fresh exotic mushrooms, trimmed and coarsely chopped (I used a mix of cremini and white)
1-1/4 cups unbleached all-purpose flour
1-1/2 tsp salt
3/4 stick cold unsalted butter, cut into 1/2 inch cubes
1 large egg
1/2 cup ice water (more if needed)
1 tbsp distilled white vinegar
1 large egg beaten with 1 tbsp water
1. Make empanada dough. Sift flour and salt together in a large bowl. Blend in butter with your fingertips or with a pastry blender until mixture resembles course meal with some (roughly pea-size) butter lumps.
2. Beat together egg, water, and vinegar in a small bowl with a fork. Add to flour mixture, stirring with fork until just incorporated (the mixture should look shaggy).
3. Turn out mixture onto a lightly floured surface and gather together, then knead gently with heel of your hand once or twice, just enough to bring dough together. Form dough into a flat rectangle and chill, wrapped in plastic wrap, at least one hour.
4. Make the filling. Preheat oven to 400˚. Combine together the squash, onion, garlic, chile peppers, and mushrooms. Toss with olive oil and a good sprinkling of salt and pepper, and spread in an even layer on a baking sheet. (The Gourmet recipe differs here, boiling and sauteing the vegetables - choose what you like best.) Roast for 25-35 minutes, until the squash is tender and the mushrooms have released their liquid, stirring every 10 minutes or so. Remove from oven and cool in pan on rack.
5. Assemble the empanadas! Keep the oven heated to 400˚. Divide dough into 12 equal pieces and form each into a disk. On a floured surface, roll out one disk into a 6 to 7 inch round. Spoon about 1/3 cup of filling onto center and brush edge of pastry with egg wash. Fold dough in half to form a half-moon, enclosing filling, and press edges together to seal. Crimp edge decoratively and move empañada to a large baking sheet. Make the remaining empañadas using the same method.
6. Lightly brush empanadas with remaining egg wash and sprinkle tops with coarse sea salt. Bake on middle rack of oven until golden, 25-30 minutes.