Slice steak across the grain into bite-sized pieces. Whisk together soy sauce, orange juice, pepper, garlic, ginger, and green onions. Toss beef to coat, then refrigerate for at least 30 minutes (can be prepared 1 day in advance).
Bring 2 quarts water to boil, add pasta, and cook 8-10 minutes, stirring occasionally.
While pasta is cooking, mix Italian dressing base with water, let stand 5 minutes. Whisk in oil and vinegar then toss with the cooked pasta in a large bowl. Let stand.
Heat a heavy skillet over high heat; add the oil. Remove beef from marinade, add to the pan and sear until browned (6-8 minutes). Stir while cooking. Liquid will start to come out of the beef; keep cooking and stirring until it has reabsorbed into the beef.
Toss pasta again to coat with dressing, add steak, and toss to combine.
Great eaten warm, or refrigerate until ready, then bring to room temperature until ready.