Pat the steak dry with paper towels. Season generously on both sides with salt, black pepper, and paprika if using. Let it rest at room temperature for 20–30 minutes before cooking.

Heat a cast iron skillet over medium-high heat. Add olive oil or avocado oil and allow it to heat until shimmering.

Place the steak in the hot skillet. Sear for 3–5 minutes per side, depending on thickness and desired doneness. Avoid moving the steak while searing to develop a proper crust.

Reduce heat to medium. Add butter, garlic, and herbs to the skillet. Tilt the pan slightly and spoon the melted garlic butter over the steak continuously for 1–2 minutes.

Remove the steak from the pan and let it rest on a plate for at least 5 minutes. This allows the juices to redistribute.

In the same skillet, add more butter if needed. Add mushrooms and cook over medium heat until they release their moisture and become golden brown, about 6–8 minutes.

Add garlic, salt, pepper, and red pepper flakes if using. Stir well and cook for another minute until fragrant.

Slice the rested steak and return it to the skillet with the mushrooms. Toss gently to coat everything in garlic butter. Finish with lemon juice and parsley if desired.