Preheat oven to 350 degrees. Line a rimmed baking sheet with parchment paper or a silicone baking mat.
Put the Chebe bread mix, 2 large eggs, oil and cheese in a large mixing bowl and combine. Add the water and mix well. The mixture will appear dry and clumpy. Dump the mixture out onto a smooth work surface and knead by hand until smooth. If the dough does not become smooth you can add a few more drops of water, but kneading it should bring the dough together. Divide the dough into 4 equal sized pieces. Lay a large piece of waxed paper out on a work surface, roll each piece of dough into a ball, place on one half of the waxed paper and fold the other half over the dough. Roll into a 7 inch circle. Repeat with remaining dough.
Remove any fat from the beef, cut into ¼ inch pieces. Place a quarter of the beef pieces on the bottom half of each dough circle leaving about a half inch of dough clear from the edge. Place the diced onion on top of the beef, season with ¼ teaspoon of salt and 1/8 teaspoon of pepper for each. Fold the dough over, forming a semi-circle. Seal the edges of the dough together well and crimp with the tines of a fork.
Place the pasties on the prepared baking sheet. Beat the remaining egg and brush on top of the pasties. Bake for 40 – 45 minutes, or until golden brown, turning the pan halfway through baking time. Place some paper towels on a plate, take the pasties off the baking sheet and place on the paper towels to absorb any excess oil.