Put a large skillet over medium-high heat and add half of the oil. When the oil is hot, add the vegetables and stir-fry until the vegetables are almost done, about 5 minutes. While the vegetables are cooking, heat a second skillet over high heat and add the remaining oil.
Cut the steak into small cubes, and stir-fry until browned on all sides, about 4 to 5 minutes.
Bring a large pot of salted water to a boil over medium heat. Separate the egg roll wrappers into 2 piles. Roll each pile up into a log. Slice the log into thin strips about 1/4-inch thick and separate them into individual noodles. Put half of the noodles into the boiling water and cook for 3 minutes. Drain and add to a serving bowl or platter. (Reserve the remaining noodles for the Online Round 2 Recipe, Japanese Noodle Bowl.)
In a small bowl combine the soy sauce, vinegar, garlic, and cornstarch and set aside.
Add the steak, along with any accumulated juices, to the pan with the vegetables. Stir the cornstarch mixture into the vegetables and cook until the sauce has thickened, about 2 to 3 minutes. Stir in the butter. (Reserve 2 cups for the Online Round 2 Recipe, Japanese Noodle Bowl).
Top the cooked noodles with the steak and vegetable mixture and serve.