Generously season the beef with salt and pepper.

Add the oil into a Dutch oven over medium heat. Add in the seasoned beef and brown on all sides before removing it with a slotted spoon and letting it rest on a paper towel lined plate to drain.

Add the onions to the pot and sautee for a couple of minutes, or until they're soft and translucent.

Add the garlic and sautee for about two minutes, stirring often

Add in the celery and mushrooms to the pot and sautee them for a couple of minutes.

Next, add in the tomato paste, thyme and rosemary and stir to evenly disperse. Stir the beef back into the pot along with the stout and the broth. Bring the stew to a rolling boil.

Stir in the brown sugar and add a bay leaf to the stew, then turn the heat down to a low simmer. Cover the pot and let the stew simmer for about 30 minutes.

Stir in the potatoes, return the cover and let the stew continue to simmer for another 30 minutes or so.

After making sure the potatoes are fork tender, bring the stew to a rapid boil, and then stir in the flour slurry until evenly incorporated.

The stew will start to thicken right away, and once it's reached the consistency you like, turn the heat off and add the frozen peas and carrots.Roll out the first pie crust. Lay it evenly in the bottom of a 9" pie pan. Gently press the sides into the glass so it rests flat against the dish. Prick the bottom several times with a fork.

Ladle the stew into the pie pan until it's even or just above the top of the dish, and then carefully lay the other pie crust out over top. Pinch the two crusts together along the rim of the dish to seal.

Brush the top of the pie lightly with egg wash and use a sharp knife to cut 2-3 slits in the top. Bake the pot pie in the oven at 400 degrees for 20-25 minutes and until the crust has turned golden and crispy.

Remove the pie from the oven and allow it rest for 5-10 minutes before slicing and serving.