Step 1: Prepare the Taco Filling

1. Sauté the Aromatics: Heat the olive oil in a large skillet or Dutch oven over medium-high heat. Once the oil is shimmering, add the finely chopped yellow onion. Sauté for 3-4 minutes, stirring occasionally, until the onion becomes soft and translucent. Add the minced garlic and cook for another minute until fragrant. Be careful not to burn the garlic.
2. Brown the Ground Beef: Add the ground beef to the skillet with the onions and garlic. Use a wooden spoon or spatula to break the meat apart into small crumbles. Cook for 6-8 minutes, or until the beef is thoroughly browned and no pink remains.
3. Drain the Grease: Once cooked, carefully tilt the skillet and use a spoon to remove any excess grease. This is a crucial step to prevent the pockets from becoming soggy. You can also transfer the meat to a colander to drain before returning it to the skillet.
4. Simmer and Thicken: Return the skillet to the heat. Sprinkle the taco seasoning (either the packet or your homemade blend) over the meat and stir to coat everything evenly. Pour in the water (or beef broth) and the tomato sauce or salsa. Stir well to combine.
5. Reduce the Sauce: Bring the mixture to a gentle boil, then reduce the heat to low. Let it simmer for 5-7 minutes, stirring occasionally. The goal is for the sauce to thicken considerably. You want a moist, flavorful filling, not a wet one, as too much liquid will make the dough difficult to seal and can lead to a soggy bottom. Once thickened, remove the skillet from the heat and let the filling cool for at least 10-15 minutes. This is another important step; adding hot filling to the cold dough can cause it to tear.

Step 2: Assemble the Taco Pockets

1. Preheat and Prepare: Preheat your oven to 375°F (190°C). Line a large baking sheet with parchment paper to prevent sticking and for easy cleanup.
2. Unroll the Dough: Open the cans of crescent roll dough. Unroll the dough onto a clean, lightly floured surface or directly onto the parchment-lined baking sheet. The dough will be perforated into 8 triangles per can.
3. Form the Rectangles: Separate the dough at the perforations. Take two triangles and press them together along the long diagonal edge to form a rectangle. Pinch the seams firmly to seal them. You will have a total of 8 rectangles (4 from each can).
4. Fill the Pockets: Spoon about 1/4 cup of the cooled taco meat mixture onto one half of each rectangle, leaving a ½-inch border around the edges. Be careful not to overfill, as this will make sealing them difficult and can cause them to burst open while baking.
5. Add the Cheese: Sprinkle a generous tablespoon or two of the shredded Mexican cheese blend on top of the meat filling in each pocket.
6. Seal the Pockets: Gently fold the empty half of the dough over the half with the filling. Press the edges together firmly with your fingers to seal the pocket. For an extra secure seal, you can use the tines of a fork to crimp the edges. This also gives the pockets a classic, decorative look.
7. Vent the Pockets: Use a sharp knife to cut one or two small slits in the top of each pocket. This allows steam to escape during baking, which prevents the pockets from becoming puffy and bursting.

Step 3: Bake to Golden Perfection

1. Apply the Egg Wash: In a small bowl, whisk together the egg and 1 tablespoon of water. Using a pastry brush, lightly brush the tops of each taco pocket with the egg wash. This will give them a beautiful, shiny, golden-brown finish.
2. Add Toppings (Optional): If you’d like, sprinkle the tops with sesame seeds, poppy seeds, or a little coarse sea salt for extra texture and flavor.
3. Bake: Arrange the sealed pockets on the prepared baking sheet, ensuring they have a little space between them. Bake for 12-15 minutes, or until the crust is a deep golden brown and the filling is hot and bubbly.
4. Cool and Serve: Remove the baking sheet from the oven. Let the taco pockets cool on the pan for at least 5 minutes before serving. The filling will be extremely hot, so this cooling period is essential to avoid burnt tongues!