Like Ireland, Cornwall is a Celtic region, so it’s no surprise that these turnovers are a favorite in pubs all over Ireland.
1. To make Dough: Sift flour and salt into bowl. Cut in margarine using pastry cutter, 2 knives, or your hands. Mixture should resemble coarse meal. Stir in 6 to 8 Tbs. ice water, or just enough to hold mixture together. Pinch dough between your fingers; if it sticks, dough is wet enough. Shape into disc, and wrap in plastic wrap. Chill 1 hour.
2. To make Filling: Heat oil in large skillet over medium heat. Add onion, celery, and garlic; cook 5 to 7 minutes, or until onion is lightly browned. Add rutabaga, potato, carrot, and thyme; cook 3 minutes, then add 1/2 cup water. Reduce heat, cover, and steam vegetables 10 to 12 minutes, or until tender.
3. Whisk 1 egg with mustard in large bowl. Stir in vegetables and Gruyère, and season with salt and pepper, if desired. Whisk remaining egg with 2 Tbs. water in separate bowl to make egg wash, and set aside.
4. Preheat oven to 400°F. Coat baking sheet with cooking spray.
5. Divide Dough in half, and roll 1 half out on floured work surface to 1/8-inch thickness. Cut out 8 discs with 5-inch round cutter. Add leftover Dough to remaining Dough, and repeat to make 8 more Dough discs. Roll each disc out to long oval; brush edges of each oval with egg wash. Place 3 Tbs. Filling on 1 side of oval, and fold Dough over to make semicircle. Press Dough around Filling to remove any air, making sure no Filling leaks out of edges. Crimp edges with fork tines to seal. Repeat with remaining Dough and Filling until you have 16 pasties. Brush tops with egg wash, and sprinkle with salt and pepper, if desired. Bake on prepared baking sheet 25 to 30 minutes, or until golden brown.