Heat oil in a large non-stick pan over medium heat. Season both sides of the fish with salt and pepper. Fry the fish until golden brown, (about 5 minutes). Carefully flip the fillets over and continue cooking for a further 2 minutes. Add in the onion and garlic, and fry until fragrant (about 2 minutes). Add in the tomatoes (burst them with your finger tips while adding them into the pan for added flavour), wine, lemon juice and olives, and continue cooking until the fish has cooked through and sauce has reduced a little. Taste test and adjust seasoning accordingly (more salt or pepper). Pour the sauce over the fish and serve immediately with the herbs.