Zest the lemon, then cut it in half and squeeze out the juice.
In a small pot, melt the butter over medium heat. Add the garlic and cook about 20 seconds until fragrant.
Add lemon juice and zest, parsley, a pinch of salt, and a few grinds of pepper. Turn off the heat and cover the pot.
Pat the fish dry. Season both sides with salt and pepper.
Scatter the flour on a plate and gently press the fish into the flour on both sides. Shake off the excess.
Heat 2 tablespoons olive oil in a skillet over medium heat. When oil is shimmering, add the fish and cook 2-3 minutes per side, depending on its thickness.
Plate the fish and spoon the sauce over the top.
