Flank Steak Sandwiches with Soy-Ginger Mayo

To make the soy-ginger mayonnaise:
Combine all ingredients in a small bowl and whisk until well blended. Cover and refrigerate until ready to use. You can make this up to one day in advance, and it really tastes best if you make it early so all the flavors come together.

To make the sandwiches:
Season your flank steak with garlic salt, salt and pepper. If you’re using a cast iron skillet, heat it to blazing hot first, add the oil and then add your flank steak. If you’re using an outdoor grill, you can skip the oil and just season the meat. Either way, cook your flank steak over high heat until the outside is seared and the inside is medium-rare. Remove from the heat and allow it to rest on a cutting board for 10 minutes. If you have a piece of foil handy, throw it over the steak to keep it warm. While the steak is resting, prep the rest of the sandwich.

Slice your baguette in half lengthwise and toast each half on the grill or in a dry skillet or griddle until lightly toasted. Spread each half liberally with soy-ginger mayonnaise. Cutting across the grain and on a bias (45 degree angle), thinly slice your flank steak and place it on the bottom half of the baguette. Top the steak with purple onion and arugula and put the lid on it. Gently press the sandwich to bring it all together, then slice into 4″ to 6″ segments and serve immediately.