In a medium sized bowl, combine the flour and salt. Cut in the butter and shortening, mixing quickly and lightly with a pastry knife, a mixer or your fingers until the mixture is crumbly. Make a well in the center of the pastry, and add the water, egg yol
Pat the dough into a 10 or 11-inch removable-bottom tart pan. Prick it all over with a fork. Bake it in a preheated 350°F oven for 10 minutes. Remove it from the oven, and let cool.
In a medium-sized bowl, beat together the eggs and milk, then stir in the cheese, oregano and thyme. Slice six of the asparagus stalks, on the diagonal, into 3/4-inch pieces. Stir the sliced asparagus, mushrooms, and salt and pepper into the egg mixture.
Pour the filling into the crust. Place the remaining 5 stalks of asparagus in a fan pattern on top of the filling.
Bake the tart in a preheated 350°F oven for about 30 minutes, or until it's set. Remove the tart from the oven, and cool to lukewarm before removing the bottom.