Season the chuck roast with the Chinese 5-spice, salt, and pepper. Turn on the saute settings on the instant pot and heat 2 tablespoon oil. Sear the chuck roast until browned on both sides, about 5 minutes. Turn off the saute settings. Add the black peppercorn, ginger, garlic, granulated sugar, soy sauce, 2 tablespoon hoisin, rice wine, and beef or chicken stock to the pot. Turn on the pressure cooking manual setting to 45 minutes. Let the steam release naturally, then remove the braised beef from the pot.
Shred the meat with two forks. In a large saute pan, combine the remaining ¼ cup hoisin with ¼ cup rice vinegar, and 2 tablespoon brown sugar. Bring the sauce to a simmer over medium heat, and continue to cook until the sugar has dissolved. Add the shredded meat, stirring to coat. Remove from heat and stir in ¼ cup chopped cilantro. Let cool completely.
Meanwhile, make the cilantro lime sauce. Combine the finely chopped cilantro with the juice of ½ lime, olive oil, red pepper flakes, and garlic. Season with salt and pepper.
Preheat the oven to 400 degrees F. Line a baking sheet with parchment paper.
Lightly dust a clean work counter with flour and roll out the puff pastry sheets to about 12x8 inches. Cut each pastry sheet into 4 equal pieces for a total of 8 pieces. Place about ½ cup of the braised beef in the center of 4 of the pastry sheets, leaving a ½ inch border.
Brush the beaten egg with water on the borders. Top each hand pie with the remaining 4 pastry sheets. Using a fork, crimp the edges, sealing the two pastries together. Lay the pastries on the prepared baking sheet. Brush the tops with egg wash and sprinkle sesame seeds on top. Bake the Chinese hoisin beef hand pies for 20-25 minutes or until golden brown. Remove from the oven and serve with the cilantro lime sauce.