How to Make It
In a medium bowl, cover the noodles with warm water and let stand until pliable, about 20 minutes; drain. Bring a medium saucepan of water to a boil and add the noodles. Cook, stirring, until al dente, about 1 minute. Drain the noodles in a colander, lifting them every few minutes to dry them.
Season the buffalo with salt and pepper. Heat 1/2 tablespoon of the oil in a small skillet. Add the steak and cook over moderately high heat until well browned and rare in the center, about 3 minutes per side. Transfer to a cutting board and let rest for at least 5 minutes.
In a small bowl, combine the remaining 3 tablespoons of olive oil with the sherry vinegar and 1/4 teaspoon each of salt and pepper.
Thinly slice the steak crosswise across the grain. Stack the slices and cut the meat lengthwise into thin strips. In a bowl, toss the steak strips with the radishes, scallions and noodles. Add the dressing, toss again and serve at once.