Heat skillet with 1 tbsp vegetable oil over medium heat.
Add 1 onion, cook and stir until onion is translucent, about 5 minutes.
Break 1 12.5 oz package frozen sandwich steak meat into skillet. Cook and stir until steak is no longer pink, about 10 minutes. Remove from heat and set aside.
Arrange 1 14 oz package egg roll wrappers on a flat surface. Place a half slice of cheese on each one.
Layer an equal amount of steak mixture on top of each cheese slice.
Roll up egg rolls according to package directions and seal edges, wetting with water, if necessary.
Heat 1 inch of 2 cups oil in a large skillet, or preheat a deep fryer to 375 degrees.
Fry the rolls in the hot oil until golden brown on all sides, about 5 minutes. Remove and drain on paper towels
Serve warm with 1/4 cup ketchup for dipping.