PASTRY PASTRY: In mixing bowl combine flour and salt; with pastry blender, or two knives, cut in margarine until mixture resembles coarse meal. Add yogurt and mix thoroughly. Form dough into 2 equal balls; wrap in plastic wrap and refrigerate for at least 1 hour. FILLING: In small nonstick skillet heat oil over medium-high heat; add onion and garlic and cook, stirring frequently, until onion is golden. Transfer to large bowl and add remaining ingredients for filling; stir to combine. PREPARE PIE: Preheat oven to 425. Roll each ball of dough between 2 sheets of wax paper, forming two 9-inch circles; fit one circle into an 8 inch pie pan and add filling. Place second circle over filling and fold edges under. If desired, flute edges. Gently pierce dough to allow steam to escape; brush pastry with beaten egg and bake until top crust is golden brown, 25 to 30 minutes.