Preheat oven to 375 degrees. Line a baking sheet with parchment paper or a silicon baking mat.
Heat 1 tablespoon of olive oil in a large skillet over medium heat. Add the onions and green pepper and cook, stirring occasionally, until softened, about 5 minutes. Add the garlic; cook for another 30 seconds, stirring. Add the ground sirloin and break it up with a spatula. Cook until the sirloin is no longer pink, about 5 minutes. Add the salt, pepper, chili powder, mustard powder and Worcestershire Sauce. Stir well. Add the ketchup and cook until the mixture is heated through.
In a large mixing bowl, combine the Chebe mix with the cheese (if using), 2 tablespoons of olive oil, 2 eggs, and ¼ cup water. Mix with a fork until combined. The mixture will be lumpy, that’s ok. Dump the mixture onto a clean work surface and knead until the dough is smooth and no longer sticky. Cut into eight equal sized pieces and roll them into balls.
Place a piece of waxed or parchment paper on your work surface. Flatten one of the balls, top with another piece of paper and roll into a 6 inch circle. Place about 1/3 cup of the Sloppy Joe mixture onto half of the circle, leaving a ½ inch border. Fold the other half of the dough over the filling, press the edges together, sealing well. Place on the prepared baking sheet and repeat with the remaining dough and filling.
Whisk the remaining egg with about 1 tablespoon of water and brush the tops of the dough with the mixture. Let dry for about a minute, brush again then sprinkle with the sesame seeds. Bake for 20 – 25 minutes or until the crusts are golden brown.