Pat the Chilean sea bass fillets dry with paper towels to ensure a crispy sear and season with salt and black pepper.

Heat 1.5 tablespoons of butter and 1.5 tablespoons of olive oil in a skillet over medium-high heat until it shimmers.

Place the seasoned fillets skin-side down in the skillet and sear for 3-5 minutes depending on thickness.

Gently flip the fillets and cook for another 3-5 minutes until golden and tender.

Check for doneness; it should flake easily and reach an internal temperature of 140-145ºF.

Melt 1/4 cup of unsalted butter in a saucepan over medium-low heat and stir in fresh lemon juice, salt, and pepper once browned.

Plate the sea bass and drizzle with the warm lemon butter sauce before serving.