Salt and pepper filets to taste. Heat 3 tablespoons of oil in a large non-stick skillet over medium high heat. Add fish and turn occasionally until cooked through. Remove filets and place on a plate. Reduce heat to medium low. Add remaining oil, garlic and thyme. Cook until garlic is golden brown, stirring occasionally. Add lemon juice and simmer until sauce thickens. Spoon sauce over filets, sprinkle with scallions and serve.