Heat the olive oil over medium heat in a sauté pan.
Transfer the onions and tomatoes to the pan and sprinkle with a bit of salt and pepper. Let them simmer for about 5 minutes, or until the tomatoes start to soften and burst. (You can press on the tomatoes lightly with your spatula to help them burst.)
Stir in the garlic; simmer for another 30 seconds.
Now pour the broth into the pan, followed by the marinara and red wine; stir in the olives and the basil.
Nestle the salmon fillets into the sauce. Once the sauce reaches a simmer, bring the heat to medium-low and cover.
Leave the salmon fillets to simmer (don't let the liquid come to a boil) for 6-9 minutes, or until the fillets reach an internal temperature of 140º F. Occasionally spoon some of the sauce over the fillets as they cook to baste them.
When the salmon is ready, garnish with some extra basil and serve.