2 cups (500 mL) all-purpose flour
1/2 teaspoon (2 mL) salt
1/2 teaspoon (2 mL) dried tarragon
1/3 cup (75 mL) butter, cubed
1/3 cup (75 mL) shortening, cubed
1 teaspoon (5 mL) vinegar
1 tablespoon (15 mL) milk
2 tablespoons (30 mL) butter
4 cups (1 L) sliced carrots
3 cups (750 mL) sliced parsnips
3 cups (750 mL) sliced mushrooms
2 onions, chopped
2 garlic cloves, minced
1 teaspoon (5 mL) dried tarragon
1/2 teaspoon (2 mL) salt
1/2 teaspoon (2 mL) pepper
2 cups (500 mL) frozen peas
2 cups (500 mL) frozen corn
3 tablespoons (45 mL) all-purpose flour
3 tablespoons (45 mL) butter
1/2 cup (125 mL) all-purpose flour
2 cups (500 mL) hot milk
1 cup (250 mL) chicken or vegetable stock
2 tablespoons (30 mL) Dijon mustard
1 teaspoon (5 mL) grated lemon rind
Pinch each salt and pepper
To make pastry (can also be made in food processor): In bowl, stir together flour, salt, tarragon and pepper. Using pastry blender, cut in butter and shortening until mixture resembles fine crumbs with a few larger pieces. In measuring cup, use fork to beat together egg and vinegar; add enough ice water to make 1/2 cup (125 mL). Pour into flour mixture all at once; stir with fork until dough just holds together. Press into disc; wrap and refrigerate for 30 minutes.
Meanwhile, in large shallow Dutch oven, melt butter over medium heat. Add carrots, parsnips, mushrooms, onions, garlic, tarragon, salt and pepper; cover and cook for about 12 minutes or until carrots just begin to soften. (Do not overcook-the vegetables will be cooked further.) Uncover and cook, stirring, until moisture is evaporated, 3 to 5 minutes, and let cool. Transfer to large bowl. Set aside to cool.
Make sauce in same pan: melt butter over medium heat; stir in flour and cook, stirring, for 1 minute, without browning. Gradually whisk in milk and stock; bring to boil, whisking constantly. Reduce heat to medium-low; cook, whisking often, for about 15 minutes or until thickened to consistency of pudding. Whisk in mustard, lemon rind, salt and pepper. Place plastic wrap directly on surface and let cool.
Add peas, corn and flour to vegetable mixture in bowl, stirring gently to blend. Pour cooled sauce over top, stirring to coat. Pour into 10-cup (3 L) oval or 13x9-inch (34x23 cm) glass baking dish. Set aside.
On lightly floured surface, roll out chilled pastry to 1/4-inch (5 mm) thick oval or rectangle. Place over vegetable mixture, trimming to leave 1-inch (2.5 cm) overhang. Pinch edges of pastry over rim of dish to seal, and flute.
Pie can be prepared to this point and frozen, then wrapped in plastic wrap and foil, and stored in freezer for up to 2 weeks. Thaw in refrigerator for 48 hours before baking.
Brush pastry top with milk, and slash steam vents. Bake at 400°F (200°C) for 50 to 60 minutes, or until pastry is golden and filling is bubbling. Let stand for 15 minutes before serving. Makes 10 servings.