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1
Heat 1 tablespoon butter in a skillet over medium heat.
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2
Thinly slice onion and add it into the skillet.
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3
Cook until soft and browned.
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4
Remove onions from the skillet with a slotted spoon and set aside.
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5
Add remaining tablespoon of butter into the skillet and increase heat to medium-high.
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6
Season both sides of each steak with salt and pepper.
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7
Add steaks into the skillet with the butter and cook 3-4 minutes on each side, according to your desired doneness.
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8
Meanwhile, slice warm ciabatta rolls in half and spread 1 tablespoon chimichurri sauce (see recipe below) on each half.
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9
Slice mozzarella and tomatoes as thinly as possible.
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10
When the steaks are cooked, place one on the bottom half of each ciabatta roll.
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11
Add the rest of the ingredients onto the sandwich in the following order, mozzarella, onions, tomatoes, arugula, and the top half of the ciabatta.
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12
Serve immediately along with red wine.
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13
For the chimichurri sauce:
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14
Combine the first six chimichurri sauce ingredients in a food processor.
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15
Blend while slowly adding olive oil.
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16
You may find that you need to add more oil to make the sauce a pourable consistency.
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17
Add salt and pepper to taste.
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18
Transfer to a small bowl or pitcher, cover tightly with plastic wrap, and refrigerate until use.
