Pat the steak dry and season well. Drying helps you get a great sear. Season both sides with kosher salt and pepper. Let it sit at room temperature for 20–30 minutes to take the chill off.
Mix the dressing. In a small bowl, whisk together lime juice, olive oil, fish sauce, honey, Dijon, grated garlic, chili flakes, and a pinch of pepper.
Taste and adjust—add more lime for brightness or honey for balance.
Prep the salad base. In a large bowl, combine greens, mango slices, cucumber, red onion or shallot, and herbs. If using tomatoes or avocado, add them now. Keep the nuts aside for crunch at the end.
Heat the pan. Set a cast iron or heavy skillet over medium-high heat.
When it’s hot, add the oil. It should shimmer but not smoke wildly.
Sear the steak. Lay the steak in the pan and don’t move it for 2–3 minutes. Flip and sear the other side for another 2–3 minutes.
Adjust time based on thickness and your preferred doneness.
Optional baste for the “million dollar” finish. Add butter, smashed garlic, and thyme to the pan. Tilt the pan and spoon the foaming butter over the steak for 30–60 seconds for extra flavor.
Check doneness. Aim for 125–130°F for medium-rare, 135°F for medium. Remember it will rise a few degrees as it rests.
Rest the steak. Transfer to a cutting board and rest for 5–10 minutes.
This locks in the juices and keeps slices tender.
Dress the greens lightly. Drizzle about half the dressing over the salad base and toss gently. You want everything just glossy, not drenched.
Slice the steak. Slice thinly against the grain. For flank, cut at a slight angle for tenderness.
Assemble. Lay steak over the dressed greens.
Spoon a little more dressing over the steak so it shines. Top with nuts for crunch and any fresh chili for heat.
Serve right away. This salad is best while the steak is still slightly warm and the greens are crisp.