Bring the steak to room temp: Take the steak out of the fridge 20–30 minutes before cooking. Pat it dry very well with paper towels.
Mix the blackening spice: In a small bowl, combine smoked paprika, garlic powder, onion powder, oregano, thyme, salt, pepper, cayenne, and brown sugar if using.
Season generously: Lightly coat the steak with 1 tablespoon of oil.
Press the spice rub all over both sides and the edges until fully covered.
Heat the pan: Place a heavy skillet (cast iron is best) over medium-high to high heat. Add the remaining oil and let it shimmer. Turn on your vent fan—the spices will smoke a little.
Sear the steak: Lay the steak in the hot pan.
Do not move it for 2–3 minutes until a dark crust forms. Flip and cook another 2–4 minutes, depending on thickness and desired doneness. For medium-rare, aim for an internal temperature of 130–135°F (54–57°C).
Optional butter baste: Add butter to the pan during the last minute.
Tilt the pan and spoon the melted butter over the steak for extra richness.
Rest and slice: Transfer the steak to a cutting board and rest for 5–10 minutes. Slice thinly against the grain.
Make the dressing: Whisk olive oil, lemon juice, Dijon, garlic, and honey with a pinch of salt and pepper. Taste and adjust acidity, sweetness, and salt.
Assemble the salad: In a large bowl, combine greens, tomatoes, cucumber, and red onion.
Toss lightly with half the dressing.
Add steak and toppings: Arrange steak slices and avocado over the greens. Sprinkle cheese and herbs. Drizzle with more dressing to taste.
Finish and serve: Add a pinch of salt, a crack of black pepper, and an extra squeeze of lemon if you like.
Serve right away while the steak is still warm.