Prep the steak: Pat the steak cubes dry with paper towels. Dry meat sears better. Season generously with salt and black pepper. If you have time, let the seasoned steak rest at room temperature for 15–20 minutes.

Prep the zucchini: Slice into half-moons about 1/2-inch thick. Toss with a pinch of salt and pepper. Blot with a paper towel if very wet.

Heat the pan: Use a large, heavy skillet (cast iron is ideal). Add 1 tablespoon oil and heat over medium-high until shimmering and just smoking.

Sear the steak in batches: Add half the steak in a single layer. Don’t crowd the pan. Sear 1–2 minutes per side until browned with a crust and medium-rare in the center. Transfer to a plate and repeat with remaining steak, adding a little oil if needed.

Make space for flavor: Reduce heat to medium. Add 1 tablespoon butter. Stir in the minced garlic and cook 20–30 seconds, just until fragrant. Don’t brown the garlic.

Cook the zucchini: Add zucchini to the skillet with a pinch of salt. Spread in an even layer and let it sit undisturbed for 2 minutes to get color. Then toss and cook another 3–4 minutes until crisp-tender and lightly browned.

Bring it together: Return steak (and any juices) to the pan. Add remaining 2 tablespoons butter. Toss until the butter melts and coats everything. Add a squeeze of lemon juice and a pinch of zest. Taste and adjust salt and pepper.

Finish and serve: Sprinkle with chopped parsley or chives. Add red pepper flakes or a dash of Worcestershire if you like. Serve hot as-is, or over mashed potatoes, rice, or cauliflower mash.