1tablespoonfresh lime juice plus 1 tsp. zest - from 1 lime
To a large skillet, melt butter over medium heat. Swirl the pan occasionally to be sure the butter is cooking evenly. As the butter melts, it will begin to foam. Once brown, add lime zest and cook for 30 seconds.
Season cod with salt and pepper; add to skillet. Cook until golden brown and cooked through, about 3 minutes per side.