If you can't find Daikon, just use thinly sliced radishes. However, I highly recommend trying to find Daikon. My favorite produce market, Wilson Farm, almost always carries it and I've seen it in a few other places. It's got a radish flavor which is more mild and palatable than proper radishes.
A piece of flank steak (at room temperature)
1 bottle of Kikkoman's Ponzo Lime Seasoned Dressing & Sauce
1/2 cup of thinly sliced Daikon (in half moons)
1/2 cup of thinly sliced cucumber (in half moons)
1/2 cup of thinly sliced carrots
Fresh baked bread
Season your flank steak liberally with salt. Then squeeze a lime and smear the juice all over the steak on both sides. Let sit for a few minutes.
In a shallow dish, add 3/4 of your bottle of Kikkoman Ponzo Lime so that the flank steak is completely covered. Let sit for about 30 minutes.
Heat up your grill pan with a light coating of oil. When it's super hot, add the flank steak. Cook steak for about 10 minutes on each side. This for me gets it medium-well but cook it to your preference. Just test it with your finger. If it's soft, it's more rare. If it's a bit tough, it's medium. If it's really tough, it's well done.
Set aside steak and let it rest. In the mean time, slice your carrots, daikon and cucumber and chop some cilantro.
Cut flank steak into very thin slices. Cut with a serrated knife and at an angle, going against the grain of the meat. The thinner the better.
Slice open a few loaves of bread and toast in the oven for a few minutes. Then fill them up with steak and vegetables.
Optional Sauce: Heat up the last of the Kikkoman Ponzo Lime in a skillet and add 1 teaspoon of cornstarch. Whisk until cornstarch is incorporated and heat until the sauce gets thick. If it gets too thick, feel free to add a tablespoon of water to thin it out. Drizzle the sauce over the meat before adding to the sandwich.