Bring a medium pot of salted water to a simmer. Add the halved fingerling potatoes and simmer gently until just tender when pierced with a fork, about 12–15 minutes depending on size. Parboiling the potatoes first ensures they cook through evenly and shortens pan time so you can crisp them without overcooking the steak.

While the potatoes cook, pat the sirloin steak dry with paper towels and season generously on both sides with salt and cracked black pepper. Drying the surface removes excess moisture so you get a better Maillard (browned) crust when searing.

Drain the potatoes and let them steam-dry in the colander for a minute. Meanwhile, warm a large heavy skillet (cast-iron preferred) over medium-high heat until it is hot — you should see faint wisps of smoke after 3–4 minutes. A very hot pan is essential to quickly form a brown, flavorful crust on the steak and to crisp the potatoes without steaming.

Add 1 tbsp olive oil to the hot skillet, swirl to coat. Place the steak into the pan and sear undisturbed for 2½–3 minutes to develop a deep brown crust. Flip and sear the other side for 2–3 minutes for medium-rare (internal temperature about 125–128°F / 52–53°C). Searing on high heat creates the flavorful crust from the Maillard reaction; timing varies by pan and stove, so use an instant-read thermometer if you have one.

During the last 30–45 seconds of cooking the second side, add the smashed garlic clove and 10 g (about 2 tsp) of the butter to the pan and tilt the pan to spoon the melted butter and garlic over the steak (basting). Basting with butter adds richness and allows the garlic aroma to lightly infuse the crust.

Remove the steak to a warm plate, tent loosely with foil, and let rest for 6–8 minutes. Resting allows juices to redistribute so the steak stays juicy when sliced.

Wipe the skillet clean with paper towels and return to medium heat. Add the parboiled potatoes cut-side down and sear until a golden crust forms, about 3–4 minutes per side. Searing the cut face gives a caramelized exterior that contrasts with a tender interior.

When the potatoes are golden on most sides, push them to one side of the pan, reduce heat to medium-low, add the remaining 15 g butter and let it foam and begin to brown (about 1–2 minutes). Swirl the pan or stir the potatoes in the butter so they become glossy. Browning the butter (watch it carefully) introduces nutty, complex flavors that elevate the potatoes beyond simple pan-frying.

Add the fresh corn kernels to the skillet with the potatoes and increase heat to medium-high briefly to char the corn, about 2 minutes, stirring occasionally so kernels brown in spots. The quick char adds smoky sweetness; because the corn is fresh and small in quantity, it will char quickly without drying out.

Stir in the chopped parsley and chives, season the potatoes and corn with salt and freshly cracked black pepper to taste, and remove from heat. The fresh herbs brighten the rich brown-butter potatoes and lift the whole dish.

Slice the rested steak thinly against the grain. Arrange the herbed brown-butter potatoes and charred corn on the plate, lay the steak slices over or beside them, and spoon any remaining pan butter from the steak (if present) over the meat for added flavor. Finish with a final pinch of flaky salt and a grind of black pepper.

Serve immediately. Enjoy the contrast of textures: a crisp, browned steak exterior and tender interior; golden, nutty potatoes; and bright, charred corn nuggets.