Step 1

Heat a large cast-iron skillet over medium-high. Sprinkle steak all over with 1 1/2 teaspoons of the salt and 1/2 teaspoon of the pepper. Add oil to skillet, and heat until shimmering. Add half of the steak pieces to skillet, keeping space between each piece. Cook, undisturbed, until browned and crispy on bottoms, about 1 minute. Flip steak pieces, and continue cooking until browned on other side, about 1 minute. Flip pieces again, and cook, turning occasionally, until most sides are browned and crispy and steak is almost medium-rare, 1 to 2 minutes. Transfer steak to a large bowl. Repeat cooking process with remaining steak pieces, transferring cooked steak to bowl with first batch; set aside. Do not wipe skillet clean.

Step 2

Reduce heat under skillet to medium; add garlic, and cook, stirring constantly, until golden brown, about 30 seconds. Add vermouth, and scrape up browned bits from bottom of skillet. Cook, stirring occasionally, until liquid is reduced to about 3 tablespoons, about 1 minute. Remove from heat; add butter, and stir until melted and creamy. Add Worcestershire sauce and remaining 1/2 teaspoon each salt and pepper. Pour mixture over steak pieces in bowl, and toss to coat. Transfer steak with butter sauce to a platter, and sprinkle with parsley. Serve immediately.