In a large skillet, warm a little oil over medium-high heat. Sear the beef on both sides, then move it to a Dutch oven.
With the skillet still hot, add some stock and use a wooden spoon to scrape up the browned bits from the bottom. Pour the stock back into the Dutch oven.
In the same skillet, heat the remaining oil, then add the butter, bacon, and mushrooms. Sauté for 5-10 minutes over medium heat until browned, then mix with the beef.
Lower the heat to soften the onions, celery, and carrots for about 10 minutes. Once they’re tender, stir in the garlic and maple sugar. After a couple of minutes, add the flour and cook for about 2 minutes.
Mix in the apple cider vinegar, stock, red wine vinegar, and herbs. Gradually stir and bring to a boil. Season to taste, then let simmer for 5 minutes before pouring into the Dutch oven.
Place the Dutch oven over medium heat and bring to a boil. Simmer for 5 minutes, then cover and transfer to the oven. Cook for 2 - 2 1/2 hours until the meat is tender. Remove from the oven and let cool completely before discarding the herbs.
Homemade Puff Pastry
In the meantime, prepare the puff pastry. In a bowl, combine the flour and salt. Add the butter and mix gently with your hands. Gradually stir in 5-6 tablespoons of iced water, adding more as needed until the dough is soft but not sticky. Wrap the dough in parchment paper and refrigerate for 10 minutes.
On a lightly floured surface, roll the dough into a rectangle measuring 12 x 4 inches, taking care not to let the butter break through.
Fold the bottom third of the pastry up to cover the middle third, then fold the top third down over the other two. Rotate the pastry counterclockwise so the folded edge is on your left. Wrap it up and return it to the refrigerator for 10-15 minutes.
Repeat the rolling and folding process three more times, refrigerating the pastry for 15 minutes between each fold. After completing all the folds, chill the pastry for an additional 20 minutes before using.
Pie Assembly
Preheat the oven to 180º C.
On a lightly floured surface, roll out the pastry. Remove the bone from the pie filling and pour into an 8 x 12 baking dish and cover it with the pastry. Brush the top with egg wash, then score a slit in the center. Bake for 25-30 minutes, or until the pastry is golden brown.
