Pat the fillets dry with paper towels and let the fillets come to room temperature, which should take about 10-15 minutes. This will help them cook evenly.
Season one side of each fillet generously with 1/4 tsp of salt and 1 tsp of cracked black pepper.
Heat oil in a medium-sized cast iron skillet or oven-safe saucepan over high heat for two minutes, or until the oil is shimmering
Carefully place the sea bass fillets into the skillet, seasoned side down. Sprinkle a little extra salt and pepper on the exposed tops.
Let the fillets sear over high heat for 2 minutes. Do not flip the fish; transfer the skillet into the oven and bake for 8 minutes, or until fish is opaque and the internal temperature is 145º F.
Plate the fish and drizzle each fillet with a tablespoon of the garlic lemon butter sauce (if you make it).
Garlic Lemon Butter Sauce (Optional).
Melt the butter in a small saucepan over moderate heat. Add the smashed garlic cloves and lemon zest to the butter.
Bring the heat to low and simmer, infusing the butter with garlic, for about 5 minutes.
Add the lemon juice and stir well to incorporate. Continue to simmer on low for 2 minutes. Discard the garlic cloves with a slotted spoon.
Garlic: Peel your cloves of garlic and, with the flat side of a chopping knife, press down on the clove to just break it open. We want to infuse the butter with the essence of garlic, but we don't want any garlic in the butter when serving.