Roll the dough out using a pasta roller machine or attachment (see notes for rolling by hand): If the dough has been in the refrigerator, then bring it out to room temperature. Cut the dough into 4 equal parts and let it rest for 20-40 minutes to make it easier to roll.
Start with one section of the dough and flatten it with your hands to about ¼ to ½ inch thick so that you can fit it into the pasta roller. Flour both sides of the dough before inserting it into the pasta roller. Start with the thickest setting, slowly working your way to the thinnest setting. You should end up with a long and very thin wide strip that you will use to cut into the pastel rectangles. If the sheet breaks, simply patch it back up together.
Cut into large squares that are between 5-6 inches x 5-6 inches. This should be about the width of the sheet of dough, so that you are simply cutting 5-6 inch sections along the length of the sheet. I can usually get 4-5 squares per sheet (4 sheets = total of 16-20 pasteis).
Take the cooled beef filling and add a heaping tablespoon or so to the pastel dough, just to the left of the center of each square so that you can fold over the right side, making pastel rectangles.
Using your fingers, moisten the edges of three left edges of dough with water. Carefully fold over the right side keeping the filling inside away from the edge so that you get dough on dough to seal. Push down to seal with fingers. Then use fork tines dipped into the cold water to crimp around the edge.
Place on a sheet pan or floured surface until ready to fry. Now, either fry them (see below) or place the sheet pan in the freezer and then transfer the pasteis to a storage container after frozen.
Heat a large, deep pot of vegetable oil to 360 F to 375 F degrees. Add 1-2 pastels at a time, lowering each carefully into the hot oil and frying for about 15 to 20 seconds until golden brown. Then place the Pastel on paper towel to absorb the excess oil.