Lightly salt and pepper six fellets. Bring a large pan to medium high heat and add butter(add enough to HEAVILY coat the bottom of the pan). When hot lay fish down(skin side first if it still has skin). Spueeze a wedge of lemon over each piece and toss in 6 thyme sprigs(reserve the other 6 for garnish).
Cook 3-4 minutes uncovered and flip. The fish should have a nice brown buttery color to it before you flip it. Add more butter if necessary. Cook and sdditional 3-4 minutes or until fish is flaky. You don't need to flip again. Add sea salt to taste and garnish with thyme sprigs.
TIP: Cook the fish in batches if your pan is not big enough. You want the fish to develop a nice buttery brown color and not steam them, which is what will happen if you crowd the pan.