From America's Test Kitchen Season 2: Simple Sandwiches
Steak sandwiches run the gamut from oversized “bombs” with greasy, gristly meat (break out the napkins) to precious restaurant concoctions (hold the truffle butter, please) with a price tag to match. We wanted to find a satisfying steak sandwich with some middle ground—easy to eat and gussied up with flavorful, but not costly, ingredients.
We started with the choice of steak, and flank steak won out over all other cuts. It’s relatively inexpensive, lean, and tender, as long as the meat is cooked correctly. For a flavorful browned crust, we generously seasoned the steak with salt and pepper and then pan-seared it in a very hot skillet on both sides until browned. To keep the steak tender and juicy, we allowed the meat to rest and then sliced it thin across the grain. Soft, squishy bread needn’t apply here—only a crusty French baguette or similar artisan-style bread would do. We slathered the bread with mayonnaise doctored with soy sauce, honey, garlic, and ginger. And to finish, thinly sliced onion and arugula scattered on top of the steak provided a little spicy bite.
If you prefer, grill the flank steak.