Cook the noodles according to the directions on the package. Drain well.
Preheat a grill or grill pan on medium heat. Season both sides of the steak with salt and pepper.
Cook the steak to your desired temperature using a thermometer (see below). Once cooked set on a cutting board to rest for 5 minutes before slicing against the grain.
In a nonstick pan on medium heat, heat both oils. Add in the onions and mushrooms. Saute for 4 - 5 minutes. Add in the carrots, snow peas, garlic, ginger, and lemongrass; saute for 2 - 3 minutes. Add the soy sauce, fish sauce, and rice wine vinegar; simmer for about 2 - 3 minutes. .
Toss in the noodles, serve the sliced steak over top. Garnish with lime wedges and cilantro.