In a sauté pan, heat 2 tablespoons of oil over medium heat. Add onion and peppers and cook for about 3 minutes, or until softened. Add the garlic and sauté for about 1 minute.
Prepare a clean, well-oiled grill to medium heat.
Add the olives and wine and cook for 4 minutes, or until the wine is reduced by half. Season to taste with salt and pepper.
Season the fish generously with salt and pepper and drizzle with the remaining tablespoon of olive oil. Grill the steaks, turning only once, for 10 minutes, or until fish is opaque.
Top each fish with the pepper and onion mixture. Garnish with the basil and lime wedges.