Steak Sandwich Recipe

Peel and finely mince the garlic clove, or grate it on a microplane. In a small bowl combine mayonnaise, minced garlic, lemon juice, Dijon mustard, olive oil, salt and black pepper. Whisk until smooth and taste; adjust salt or lemon if needed. Cover and refrigerate while you prepare the rest. Makes enough for 4 sandwiches.

Slice the yellow onion in half lengthwise and cut into thin half-moons (about 1/8–1/4 inch thick).

Heat 1 tablespoon olive oil and 1 tablespoon butter in a medium skillet over medium heat until butter is melted and foaming.

Add the sliced onions and 1 teaspoon salt. Cook, stirring occasionally, for 10–15 minutes until softened and beginning to brown. If you want sweeter, deeply caramelized onions, reduce heat to medium-low after 10 minutes and continue to cook 15–20 more minutes, stirring more frequently; add 1 teaspoon brown sugar during the last 5 minutes if using.

Once onions are softened and golden (or deeply caramelized), remove from heat and set aside.

Remove steak from the refrigerator 20–30 minutes before cooking to bring it near room temperature. Pat dry with paper towels.

Season both sides generously with kosher salt and freshly ground black pepper (use roughly the listed amounts or to taste). Press seasoning into the meat.

Heat a heavy skillet (cast-iron preferred) over high heat until very hot. Add 1 tablespoon olive oil and 1 tablespoon butter; when the fat is shimmering and the butter foaming, add the steak.

Sear the steak undisturbed for 3–4 minutes to develop a brown crust. Flip and sear the other side 3–4 minutes for medium-rare (internal temp ~130–135°F / 54–57°C). Adjust time +/- 1–2 minutes depending on thickness and desired doneness.

Remove steak to a cutting board and let rest 5–10 minutes to allow juices to redistribute. Slice thinly across the grain into strips about 1/4 inch thick.

Halve the sandwich rolls or ciabatta. Spread about 1 tablespoon of butter on each cut face (total 2 tablespoons).

Heat a clean skillet or griddle over medium heat. Place buttered cut sides down and toast until golden brown and crisp, 1–2 minutes. Remove from heat.

Spread about 1–2 tablespoons of the prepared aioli on the bottom half of each roll (adjust to taste).

Layer a handful (about 1/2 cup) of arugula or lettuce on top of the aioli if using. Pile sliced steak evenly across the 4 sandwiches (about 4 oz steak per sandwich).

Top the steak with a generous portion of the cooked onions (about 2–3 tablespoons per sandwich). Finish with a drizzle of any resting juices from the cutting board if desired, and spread a little aioli on the top half of the roll if you like.

Close the sandwiches, press gently, slice in half if desired, and serve immediately.