Place flour, shortening, butter and salt in food processor and pulse 12 times. While pulsing, add water, approx. 1 T at a time, until mixture is coarse, not smooth. The dough should have bits of butter and shortening throughout. If dough seems too dry, add drops of ice water until it comes together. Do not overwork. Gather the dough and divide into 8 equal pieces. Quickly form into discs, wrap in plastic and refrigerate for at least 1 hr.
Place cut beef and beer in a small bowl or resealable bag and marinate 1 hr, or overnight. Remove beef and reserve liquid. Pat dry with paper towels, and season well with salt and pepper.
In a large skillet over med high heat, add 1 T oil and sauté beef until browned. Remove from pan and set aside.
Add remaining 2 T oil to the pan, add onion and brown; add potatoes and cook until softened. Add mushrooms, cook 2 min. Sprinkle with flour. Sauté 2 min and add reserved liquid, stir until thick. Remove from heat. Add cream, beef and parsley. Salt and pepper to taste, chill and add cheese. Filling can be made one day ahead.
To assemble, roll discs into 7” rounds, 1/8” thick on a floured surface. Transfer to parchment-lined cookie sheets. Place 1/2 c of filling on each and spread, leaving 1 1/2” edge. Fold edge over filling, pleating it to form an open-faced pie. Brush the sides twice with egg. Sprinkle with salt and pepper.
Preheat oven to 350°. Bake 35-40 min, until bubbly and golden brown. Serve warm.
*Substitute sirloin with another tender cut, such as tenderloin. Do not use tougher cuts, such as stew meat.