Step 1: Prep the Steak
Pat the sirloin steak completely dry with paper towels. This is the single most important step for achieving a proper sear. Cut the steak into uniform, 1-inch to 1.5-inch cubes. Try to make them as even as possible so they cook at the same rate. Season the steak bites generously on all sides with kosher salt, black pepper, and smoked paprika or garlic powder if using. Let them sit at room temperature for 15-20 minutes while you prep the other ingredients. This takes the chill off for more even cooking.

Step 2: Sear the Steak Bites – The High-Heat Blast
Heat a large, heavy-bottomed skillet (cast iron or stainless steel are ideal) over medium-high to high heat until it is smoking hot. Add the high-smoke-point oil and swirl to coat. Working in batches to avoid overcrowding (which steams the meat), carefully add the steak bites in a single layer with space between them. Do not move them for 2-3 minutes! This allows a deep, brown crust to form. Using tongs, flip each piece and sear for another 2-3 minutes for medium-rare, or until your desired doneness. Transfer the seared bites to a clean plate. Repeat with remaining batches, adding a bit more oil if needed.

Step 3: Deglaze and Build the Sauce Foundation
Once all steak bites are out, reduce the heat to medium. There will be glorious browned bits (fond) stuck to the pan. Pour in the white wine, broth, or lemon juice. Using a wooden spoon, scrape vigorously to dissolve all those flavor-packed bits into the liquid. Let it simmer for about 30 seconds until slightly reduced.

Step 4: Create the Garlic Butter Sauce
Add 2 tablespoons of the cold butter to the pan. Once melted, add the minced garlic, red pepper flakes (if using), and dried herbs (if using dried instead of fresh). Cook, stirring constantly, for just 45-60 seconds until the garlic is fragrant but NOT burned. Burnt garlic will turn bitter.

Step 5: Mount the Sauce & Finish
Reduce the heat to low. Add the remaining 4 tablespoons of cold butter, one piece at a time, swirling the pan or whisking constantly until each piece is mostly melted before adding the next. This gradual incorporation, called monter au beurre, creates a smooth, glossy, emulsified sauce. Remove the pan from the heat entirely. Stir in the fresh herbs (parsley, thyme, rosemary) and the fresh lemon juice. The residual heat will wilt the herbs perfectly. Taste the sauce and adjust seasoning with salt and pepper.

Step 6: The Grand Reunion & Final Glaze
Return all the seared steak bites and any accumulated juices on the plate back to the skillet with the finished garlic butter sauce. Gently toss and stir for about 30-60 seconds, just until the steak is reheated and every piece is luxuriously coated in the glossy, herb-flecked butter.

Step 7: Serve Immediately
Transfer the steak bites and every last drop of sauce to a warm serving platter or bowl. Garnish with an extra sprinkle of fresh parsley and a pinch of flaky sea salt. Serve immediately while hot and sizzling. Provide crusty bread on the side for mandatory sauce-mopping, and lemon wedges for those who want an extra bright note