Pastry for 2-crust pie, homemade or purchased 
1 pound lean ground beef 
1 tablespoon olive oil 
1 cup chopped green onion 
1 red bell pepper, chopped 
1 rib celery, chopped 
1 medium carrot, chopped 
1 small summer squash or zucchini, chopped 
3 tablespoons all-purpose flour 
1/2 cup tomato sauce 
1/2 cup grated Parmesan cheese 
1 scant teaspoon dried leaf thyme 
1 teaspoon salt 
1/2 teaspoon ground black pepper 
1 egg, mixed with 1 tablespoon of water, for glaze 

If pie pastry is not pre-made, prepare pie crust; divide dough in half for top and bottom crust. Wrap dough portions in plastic wrap; chill for about 30 minutes. Prepare filling. In a large skillet over medium heat, cook ground beef in olive oil until no longer pink. Transfer beef to a bowl with slotted spoon. Drain off excess grease, leaving a few teaspoons. Put skillet back on medium heat; add green onion, red bell pepper, chopped celery, squash, and chopped carrot. Cook, stirring often, until softened, about 8 to 10 minutes. Return beef to skillet and stir in flour; stir and cook for 1 minute. Remove from heat and stir in tomato sauce, Parmesan cheese, thyme, salt, and pepper. Set aside while rolling dough.

Roll half of chilled dough out on a floured surface to a circle about 12 inches in diameter; place on an ungreased baking sheet. Spoon beef filling over the dough circle, to within 2 inches of the edge. Roll out remaining dough to a circle about 11 inches; place over filling. Fold edges of bottom crust circle over the top circle; pinch to seal all around.

Brush top of beef pot pie with egg and water mixture. 

Bake beef pot pie at 400° for about 50 minutes. Place baking sheet with beef pot pie on a rack to cool for about 5 minutes before serving.

Beef pot pie serves 6.