Temper the steak: Pull the steak from the fridge 30 minutes before cooking.
Pat it very dry and season generously with kosher salt and black pepper on both sides.
Prep the salad base: Slice tomatoes into 1/2-inch rounds or halve cherry tomatoes. Slice mozzarella into thick rounds. Rinse and dry the arugula.
Tear basil leaves just before serving for maximum aroma.
Make a quick dressing: In a small bowl, whisk 2 tablespoons extra-virgin olive oil with 1 tablespoon red wine vinegar or lemon juice, a pinch of salt, pepper, and the grated garlic if using. Taste and adjust acidity or salt.
Heat the pan: Set a heavy skillet (cast iron works best) over medium-high until very hot. Add 1–2 teaspoons neutral or light olive oil and swirl to coat.
Sear the steak: Lay the steak in the pan.
Don’t move it for 2–3 minutes until a deep crust forms. Flip and cook another 2–3 minutes for medium-rare, adjusting time based on thickness.
Optional baste: Reduce heat to medium, add the butter, and spoon the foaming butter over the steak for 30–45 seconds. This adds richness and a glossy finish.
Rest the steak: Transfer to a cutting board and rest 7–10 minutes.
This keeps the juices inside. Slice against the grain into 1/4-inch strips.
Assemble the greens: Toss arugula lightly with the quick dressing and spread it on a large platter as a bed.
Layer the Caprese: Arrange tomato and mozzarella slices over the greens, tucking in basil leaves. Season the tomatoes and cheese with a pinch of salt and pepper for maximum flavor.
Add the steak: Fan the steak slices over the salad.
Drizzle with balsamic glaze and a little extra-virgin olive oil. Finish with flaky salt and more basil.
Serve immediately: This salad is best when the steak is slightly warm and the tomatoes are room temperature.