3 sweet potatoes
1 tablespoon extra virgin olive oil
2 vidalia onions, peeled and sliced
2 teaspoons balsamic vinegar
pinch of dried sage
pinch of cayenne pepper
1 cup gruyere cheese
2 sheets puff pastry, thawed
Preheat the oven to 425 degrees. Peel and chop the sweet potatoes, toss in olive oil and a pinch of salt and pepper. Bake for 45 minutes, turning the potatoes frequently to avoid them browning too much on one side. Once cooked through, set aside in a large bowl to cool.
Heat oil in a pan and add onions with a sprinkle of salt and pepper. Cook for 8 minutes on medium heat, until they start to become translucent. Add balsamic vinegar and let the onion caramelized for a few minutes. Add onions to the potatoes. Add sage, a dash of salt and cayenne pepper, and gruyere cheese to the vegetables.
Roll out the puff pastry, and cut both sheets into four squares. Put the vegetable mixture onto 4 of the sheets, leaving a 1" border of dough around the edges. Make an egg wash by whisking the egg with a tablespoon of water. Brush the borders of each pastry with the egg wash. Add the tops of each hand pie and crimp the edges with a fork. Slit the tops of each and put on a greased baking sheet. Bake for 30-35 minutes, or until the pastry is puffed up and golden brown. Allow to cool before serving.