PREPARE PASTRY DOUGH: In medium bowl, with fork, stir flour and sugar. With pastry blender or two knives used scissor fashion, cut margarine or butter into flour mixture until mixture resembles coarse crumbs. Add egg; mix lightly with fork until dough is just moist enough to hold together. (Or, in food processor with knife blade attached, blend flour, margarine or butter, cut into 8 pieces, and sugar until mixture resembles coarse crumbs, about 10 seconds. Add egg through feed tube; blend 15 seconds more or until dough holds together and leaves side of bowl.) With hands, shape dough into ball. Wrap with plastic wrap and refrigerate 1 hour; trim edge. With fork, prick tart shell in many places to prevent puffing and shrinkage during baking.
Line tart shell with foil; bake 10 minutes. Remove foil; again prick dough. Bake 10 minutes longer. Remove tart shell from oven; turn oven control to 425°F.
PREPARE STREUSEL TOPPING: In small bowl, combine flour and lightly brow sugar. With pastry blender or two knives used scissor fashion, cut margarine or butter into flour mixture until mixture resembles coarse crumbs. Refrigerate.
Preheat oven to 350°F On lightly floured surface, with floured rolling pin, roll out dough into round about 1 inch larger all around than 10inch tart pan with removable bottom.
Ease dough into tart pan to line evenly.
Drain pears; pat dry with paper towels. Cut each pear half lengthwise into ¼ inch thick slices, being careful to keep slices from each half together. Arrange pears on mincemeat, fanning slices slightly.
With spoon, evenly sprinkle Streusel Topping over sliced pears in tart shell.
Bake tart 15 to 20 minutes until filling is heated through and crust and topping are lightly browned. Cool tart slightly in pan on wire rack.
Remove side of pan. Serve tart warm or cool completely to serve later. 10 servings. Begin about 2 hours before serving or early in day.