Brush filets on both sides with olive oil and then sprinkle with 1 teaspoon salt and pepper.
Put remaining olive oil in non-stick skillet and heat to medium-high.
Cook filets one at a time about 3-4 minutes per side, or until fish is cooked through. Remove and keep warm.
Melt butter in skillet over low heat. Add garlic and cook until garlic is fragrant and just starting to brown. Add wine, heat to boiling over medium heat. Cook until reduced by half.
Take off heat and let cool about 3 minutes and then stir in lemon juice, cream, thyme and salt. Simmer for about 5 minutes.
Stir flour and water or stock together with whisk until no lumps remain. Whisk into sauce and cook over medium low heat until sauce is thickened, stirring constantly.
Ladle sauce onto plates and top with fish, or put fish on plates first and then add sauce. Garnish, if desired, with lemon slices and additional thyme.