Dry scallops gently with paper towel. Put oil in medium frying pan and turn on heat to medium. Add butter, and while butter flour on both sides. When butter is starting to foam, add scallops to pan. Cook until scallops are barely browned on both sides and starting to feel firm, but not until they feel completely firm, about 2 minutes per side for the initial browning.
When both sides are browned slightly, add garlic, lower heat a little, season with salt and pepper as desired, and cook about 2 minutes more, either stirring or shaking the pan so the garlic is well distributed around all the scallops. Garnish with parlsey and serve hot, with lemon slices if desired.