How to Make It
Preheat the broiler. Rub the olive oil over the flank steak and season with the salt and pepper. Place the steak under the broiler and cook until browned, 6 to 7 minutes per side. Remove from the broiler, cover with foil, and set aside.
In a small bowl, whisk together the soy sauce, lime juice, sesame oil, ginger, fish sauce, and jalapeño. In a large bowl, combine the basil, cilantro, cucumber, onion, and bean sprouts and toss well with the soy dressing. Arrange the noodles on top.
Slice the steak into 1/4-inch pieces, cutting against the grain, and place over the noodles. Garnish with additional basil and cilantro, if desired. Serve.
To make up to 1 day ahead, prepare and store separately in the refrigerator: steak, dressing, vegetables, and noodles. Assemble up to 3 hours before serving.