01 - In a mixing bowl, combine the thinly sliced steak with soy sauce, black pepper, and garlic powder. Toss to coat evenly and set aside to marinate while you prepare the vegetables.
02 - Heat a large skillet over medium-high heat with a splash of vegetable oil. Add the diced onion and bell peppers. Sauté for approximately 4–5 minutes, until softened and lightly golden. Transfer the sautéed vegetables to a separate bowl.
03 - Add the marinated beef to the same skillet. Sear for 2–3 minutes until just browned and cooked through. Return the sautéed vegetables to the skillet with the beef and toss to combine. Remove from heat and allow to cool slightly.
04 - Stir the shredded provolone cheese (and softened cream cheese, if using) into the beef and vegetable mixture. Continue stirring until the cheese is melted and evenly distributed throughout the filling.
05 - Lay out an egg roll wrapper with one corner facing you. Place approximately 2 heaping tablespoons of the filling across the center of the wrapper. Fold the bottom corner up over the filling, then fold in the side corners. Roll up tightly to form an egg roll. Brush the top corner with the beaten egg to seal.
06 - Heat about 2 inches of vegetable oil in a deep frying pan or Dutch oven to 350°F (180°C). Carefully fry the assembled egg rolls in batches for 3–4 minutes, turning occasionally, until they are golden brown and crisp. Remove the fried egg rolls and drain them on paper towels.
07 - Serve the hot, crispy egg rolls immediately. They are delicious on their own or can be served with dipping sauces like cheese sauce or spicy ketchup.