Begin by preheating your oven to 375°F (190°C). This ensures a perfectly baked pocket at the end.
In a large skillet, over medium heat, brown the ground beef (or turkey). Use a spatula to break it up into small pieces as it cooks, for about 7-10 minutes, or until well-cooked and no longer pink. Once cooked, drain off any excess fat to keep it from being greasy.
Incorporate the finely chopped onion into the skillet, stirring and sautéing for an additional 3-4 minutes until the onion becomes translucent and fragrant.
Add the diced dill pickles, ketchup, mustard, salt, and pepper to the mixture. Stir to combine and let it cook for another 2 minutes. Once everything is well-mixed, remove the skillet from the heat and allow the mixture to cool slightly.
While the mixture cools, unroll the crescent roll dough and gently separate it into the triangles as indicated on the package. Lay them out on a clean surface.
On the wider end of each triangle, spoon a generous amount of the beef mixture, and top it with a sprinkle of shredded sharp cheddar cheese. Be careful not to overfill to prevent bursting during baking.
Start rolling the dough over the filling from the wide end, ensuring to tuck in the sides as you go to create a sealed pocket. This will help keep all the delicious filling inside.
Arrange the filled pockets on a baking sheet lined with parchment paper. For an extra crunch and flavor, sprinkle sesame seeds lightly on top if desired.
Transfer the baking sheet to the preheated oven, and bake for 12-15 minutes. Keep an eye on them until the dough turns golden brown and is cooked through.
Once baked, remove from the oven and allow them to cool for a few minutes before serving to avoid any hot filling burns.