Combine all the marinade ingredients in a bowl with a whisk. Place the steak in a lidded container with the marinade, making sure the steak is covered. Refrigerate for 2 to 3 hours or up to overnight.
Add all of the broth ingredients to a stock pot and bring to a boil over high heat; reduce the heat to medium-low, cover partially and simmer for 30 minutes.
Preheat the oven to 350°F.
Heat a grill pan or large skillet over a medium-high heat.
Pat the steaks dry and quickly sear, 2 to 3 minutes per side, or until grill marks appear. Transfer to a sheet pan and roast to the desired doneness (for medium rare the internal temperature should be 135°F, 125°F for rare).
Transfer the steaks to a cutting board, and let rest for 10 minutes before slicing or serving.
Cook the noodles in a large pot of salted boiling water according to package instructions and stir in the canola oil to prevent sticking.
Steam the snow peas in the microwave or a small pot of salted boiling water for 2-3 minutes, then rinse with cold water.
To serve, divide the noodles between 4 serving plates. Place the steak slices, snow peas, and radishes over the noodles and scatter the scallion on top. Pour in the broth.