Soak rice noodles according to package directions; set aside. Drain well.
Meanwhile, toss together steak, cornstarch, 1 tablespoon soy sauce, and ½ teaspoon sugar in a medium bowl. Whisk together oyster sauce, dark soy sauce, fish sauce, remaining 2 tablespoons soy sauce, and remaining 1 teaspoon sugar in a small bowl; set both aside separately.
Heat oil in a large wok or heavy-bottomed skillet over high. Add half of beef in an even layer; cook, undisturbed, until browned on bottom, about 1 minute. Turn and cook until just browned on other side, about 30 seconds. Transfer beef to a plate, reserving oil in wok. Repeat process once more with remaining beef; transfer to plate.
Remove wok from heat; add garlic, minced chiles, and ginger. Return wok to heat over medium-high; cook, stirring constantly, until fragrant, about 15 seconds. Add onion; cook, stirring often, until slightly softened, 45 seconds to 1 minute.
Add reserved noodles and oyster sauce mixture. Cook over medium-high, tossing or stirring often, until noodles absorb sauce and are tender, 1 to 2 minutes. Add browned beef; cook, tossing occasionally, until evenly combined, about 30 seconds.
Remove wok from heat; add basil, and toss until just wilted, about 30 seconds. Divide noodles evenly among 4 bowls. Garnish with sliced chiles and additional basil; serve immediately.
