Combine 2 tbs olive oil, soy sauce, Worcestershire sauce, 3 minced garlic cloves, 1 tsp black pepper, 1 tsp kosher salt and chopped rosemary in a shallow dish or zip-top bag. Add the steak, turn to coat, press out excess air (if using a bag) and refrigerate for 30 minutes to 2 hours. If short on time, marinate at room temperature for 20–30 minutes.

Bring to room temperature

Remove the steak from the refrigerator 20–30 minutes before cooking so it comes closer to room temperature. Pat the steak dry with paper towels just before cooking to ensure good sear.

Skillet Vegetables & Finish

Par-cook potatoes (if using raw potatoes)

If using baby potatoes or raw cubed potatoes, place them in a pot of cold salted water, bring to a boil, and simmer 6–8 minutes until just tender when pierced. Drain and set aside. (If using pre-cooked or small fingerlings, skip this step.)

Preheat skillet and sear steak

Heat a heavy cast-iron or stainless-steel skillet over high heat until very hot, about 4–5 minutes. Add 1 tbs olive oil and swirl to coat. Place the steak in the pan and sear without moving for 2–3 minutes to develop a brown crust. Flip and sear the other side 2–3 minutes for medium-rare (internal temp ~125–130°F / 52–54°C). Adjust time for thickness and desired doneness. Use tongs to hold the edges for 20–30 seconds to render fat if present.

Rest the steak

Transfer the seared steak to a cutting board and tent loosely with foil. Let rest 8–10 minutes while you cook the vegetables. Resting redistributes juices and finishes cooking through carryover heat.

Cook the vegetables

In the same skillet (wipe out only if there’s excessive burnt bits but keep fond for flavor), melt 1 tbs butter over medium-high heat. Add sliced onion and bell pepper and sauté 3–4 minutes until they begin to soften. Add mushrooms and par-cooked potatoes and cook 4–5 minutes, stirring occasionally, until vegetables are browned and tender. Add the 2 minced garlic cloves and cook 30–45 seconds until fragrant.

Deglaze and finish

Pour in 1 tbs stock and 1 tsp balsamic vinegar to deglaze the pan, scraping up browned bits with a wooden spoon. Stir in chopped parsley, adjust seasoning with 1 tsp salt and 1 tsp pepper (or to taste). Return the steak slices to the skillet to warm for 1 minute, spooning pan juices over the meat.

Slice and serve

Slice the steak thinly across the grain. Arrange slices over the skillet vegetables or mix together in the skillet. Serve hot with lemon wedges and optional hot sauce or steak sauce at the table.