In a large skillet over medium-high heat, melt the butter until foamy, but not browned.

Rinse the scallops under cold water and pat dry with paper towels.

Dump the flour onto a shallow plate.

Season the scallops on both sides with salt and pepper and then roll in the flour.  Shake off the excess.

Add the scallops to the skillet in a single layer, without crowding the pan.  Work in batches, if necessary.

Cook the scallops, undisturbed until golden brown, for about 2 minutes.  Flip each scallop and cool the other side until golden and translucent in the center, about another 1-2 minutes.

Remove the scallops from the pan and keep warm.

Add the garlic to the pan and cook for one minute, stirring constantly.

Pour in the white wine and lemon juice.

Bring to a boil and cook for one minute.

Whisk in the mustard and simmer the sauce until it is reduced by about half – 2 minutes.

Remove the pan from the heat and whisk in the butter.  Whisk vigorously as it melts to bring the sauce together.  

Taste the sauce and adjust for seasoning.  If necessary, add more salt and pepper to taste.

Return to the heat.  Add the scallops back to the pan and turn in the sauce.  Allow the scallops to warm, while turning gently in the sauce – about 2 minutes.

Sprinkle with parsley and serve hot.