In a large skillet over medium-high heat, brown the ground beef and diced onions until meat is thoroughly cooked and onions are translucent.
Drain excess grease from the skillet.
Stir in salt, pepper, garlic powder, and Worcestershire sauce; mix well and remove from heat.
Allow the beef mixture to cool slightly, then stir in the shredded cheddar cheese until just combined.
Lay an egg roll wrapper on a clean surface in a diamond shape and place approximately 3 tablespoons of the filling in the center.
Fold the bottom corner up over the filling, tuck in the side corners, and roll tightly toward the top corner.
Brush the top corner with the beaten egg to seal the edge securely.
Heat vegetable oil in a heavy pot or deep fryer to 350°F (175°C).
Fry the egg rolls in batches for 3-5 minutes, turning occasionally, until golden brown and crispy.
Remove with a slotted spoon and drain on paper towels before serving hot.