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Export 7 ingredients for grocery delivery
Step 1
Seasoning the steak generously with salt and pepper.
Step 2
Add 1 tablespoon of oil to a large cast-iron skillet over high heat. Once shimmering, adding the steak.
Step 3
Fry the first side for 2 minutes and then flip over.
Step 4
Fry the other side for 3 more minutes until the steak is nicely browned on the outside and still medium rare in the middle. Remove from heat and let it rest for 5 minutes. Then cut it into thin slices.
Step 5
Turn the heat to medium and add the rest of the oil to the skillet.
Step 6
Add onions and cook for about 9-10 minutes or until golden and softened, stirring frequently. Transfer to a plate and set aside.
Step 7
Lightly butter the bread and toast until golden.
Step 8
Place the bottom half of the bread on a plate and top with arugula and caramelized onions.
Step 9
Add a layer of the thin steak slices, and spread mustard on top.
Step 10
Cover the sandwiches with the top half of the bread. Serve immediately or pack for lunch.