Pastry: Blend flour and salt in a large mixing bowl. Using a pastry blender or your fingers, work in shortening until coarse crumbs form. Sprinkle 2 tbsp (30 mL) water over dough; using a fork, mix in until dough is slightly moist. Add remaining water if needed. Shape dough into a ½” (1 cm) thick flat disc. Wrap in plastic wrap and refrigerate for 30 minutes.
Roll dough on a floured board into a circle measuring 12” (30 cm). Loosely roll dough around rolling pin, and then unroll easing dough into 9” (23 cm) deep dish pie plate.
Filling: Cook asparagus according to package directions, 2 minutes. Drain well, pat dry and cut into 2” (5 cm) pieces. Set aside.
Sprinkle pie shell with onion and red pepper. Whisk eggs with evaporated milk, mustard, salt and pepper. Stir in cheese and dill. Pour into shell. Scatter asparagus on top.
Bake on lower shelf of preheated oven for 20 minutes. Reduce heat to 350°F (180°C) and bake for 35 to 45 minutes until set. Let stand 15 minutes.