Pat meat dry. Add oil to Dutch oven. Sear the meat on all sides. Remove to plate. Deglaze the pan with 1/4 cup beer. Add the onions and garlic. Cook until beer has mostly evaporated. Stir in the tomato paste. Add the beer, broth, worcestershire and bouillon.
Add the beef back to the pan. Throw in the sprigs of thyme Bring to a boil. Reduce to a simmer and simmer 1 to 1 1/2 hours. Until meat is tender. Remove the sprigs of thyme
Meanwhile cook the carrots and potatoes in boiling salted water. Drain and set aside.
In a pie pan roll out 1 sheet of puff pastry and press into pan. Preheat oven 425 degrees. Place the pie pan in oven and bake just until the bottom crusts starts to brown a bit.
Remove from oven and pour the potatoes and carrots into it.
Mix the cornstarch and water together and thicken the beef broth a bit. Pour it into the pie shell.
Place the other puff pastry sheet on top of pie. Cut any excess off the sides. Mix the egg and water and brush over the top.
Bake for 25 to 30 minutes until dough is nicely browned.