Bring a large pot of water to a boil. Cook the noodles according to package instructions. Drain, rinse under cold water and set aside.
Meanwhile, whisk together the vinegar, honey and a large pinch of salt in a small microwave-safe bowl. Add the shallot and toss to coat. Microwave for 1 minute. Let cool and then drain, reserving 1/4 cup of the pickling liquid.
Position an oven rack 5 to 6 inches below the broiler and preheat. Line a baking sheet with foil.
Put the flank steak on the prepared baking sheet and sprinkle all over with salt and pepper. Rub the steak with 1/4 cup of the Korean Gochujang Cooking Sauce and let marinate at room temperature for 15 minutes.
Broil the steak (without turning) until nicely browned and firm, with some give when pressed in the thickest part, 6 to 8 minutes for medium-rare. Let rest for 5 minutes.
Toss the rice noodles with the scallions, carrots, sesame oil and reserved pickling liquid in a medium bowl. Season with salt and pepper.
Slice the steak thinly against the grain. Scatter the pickled shallots over top and serve with the rice noodle salad and remaining cooking sauce on the side.
Copyright 2018 Television Food Network, G.P. All rights reserved.