Heat 3 quarts (2.8 L) of oil in a large pot until it reaches 350°F (180°C). Set a wire rack over a baking sheet.
Heat the remaining tablespoon of vegetable oil in a large cast-iron skillet over high heat. Add the ground beef, 1 teaspoon of salt, and 1 teaspoon of pepper, and cook for 10 minutes, or until browned. Remove the beef from the pan, leaving the drippings behind, and set aside.
In the same pan, cook the onion for 5 minutes, or until softened.
Push the onions to one side of the pan, and add the green pepper to the other side. Cook for 5 minutes, or until softened.
Return the ground beef to the pan. Add the remaining teaspoon of salt, remaining teaspoon of pepper, the oregano, brown sugar, garlic, Worcestershire sauce, and ketchup, and stir to combine. Add the tomato sauce and stir well.
Lay an egg roll wrapper on a clean surface. Brush a ½ inch (1 cm) border all around with egg wash.
Place two tablespoon filling of sloppy joe filling in the center of the egg roll wrapper. Fold one corner of the wrapper over the filling. Fold the sides over the folded corner. Continue rolling to seal the egg roll. Repeat with the rest of the wrappers and filling.
Fry the egg rolls, about 2 at a time, for about 2 minutes on each side, until evenly golden brown. Set the fried egg rolls on the wire rack to drain, and let cool for 10 minutes.