Prepare the fish: Season the fish fillets with salt, pepper, and lime juice. Set aside for 10-15 minutes to marinate.
Cook the fish: Heat olive oil in a pan over medium heat. Once hot, place the fish fillets in the pan and cook for 3-4 minutes on each side until golden and cooked through. Remove and set aside.
Prepare the basil sauce: In the same pan, add sliced onions and garlic. Sauté for 2 minutes until soft. Add soy sauce, honey (if using), and chopped basil leaves. Stir well to combine.
Combine: Return the fish fillets to the pan, spoon the basil mixture over them, and cook for an additional 1-2 minutes to allow the flavors to meld together.
Serve: Garnish with extra basil leaves or a slice of lime if desired. Serve with rice or a light salad for a complete meal.