In medium bowl, mix flour, salt, thyme and oil until all flour is moistened.
Sprinkle with cold water, 1 tablespoon at a time, tossing with fork until all water is absorbed.
Gather pastry into a ball.
Place pastry between 2 sheets of waxed paper.
With rolling pin, roll into 8½-inch round; set aside, covered with towel.
Heat oven to 425°F.
In 12-inch skillet, melt butter over medium-high heat.
Add mushrooms; cook 5 to 7 minutes, stirring frequently, until mushrooms are tender.
Stir in 1½ cups half-and-half and the sauce mix.
Heat to boiling over medium-high heat, stirring constantly.
Stir in vegetables.
Cook 2 to Minutes, stirring frequently, until thoroughly heated.
Spoon vegetable mixture into ungreased 9½-inch deep-dish pie plate.
Remove top waxed paper from crust; cut about 1-inch hole in center of crust.
Carefully invert crust over filling; remove remaining waxed paper.
Cut small slits in several places in crust.
Brush crust with 1 teaspoon half-and-half.
Bake 25 to 30 minutes or until crust is golden brown.
Let stand 10 minutes before serving.