Winter Vegetable Jalousie

Finely dice the potatoes and boil for about 6 minutes. Cut the carrots and leek into strips. Cook the chopped onion in 3 tablespoons of oil until soft, then add the carrots and leek. Continue to cook for 5 minutes, then add the drained potatoes; season with salt and pepper and cook for 5 more minutes. Spread the thawed puff pastry on a lightly floured work surface. Cut out 16 rectangles (about 2x4 inches). Spoon the vegetables and the cubes of cheese on half the rectangles, brush the edges with egg, close the with the other half of the dough, score with 5 cuts and brush the top with egg. Bake at 350°F for 15 minutes.