This is adapted from my local newspaper. Any mild white fish will work here. This dish is easy to prepare. Kalamata olives are the black Greek olives, but you can substitute nearly any olive you prefer.
In a deep-sided skillet or Dutch oven, heat oil over medium heat. Saute onions, stirring occasionally, until they being to soften, about 3 minutes. Stir in oregano, thyme, tomatoes, olives, capers and half the parsley. Simmer until tomatoes break down and you are left with a chunky sauce 10 to 15 minutes.
Season fish with salt on both sides. Push the sauce to one side so that you have a thin layer of sauce on the other. Lay your fish over the thin sauce side and then cover the fish with all the sauce. Place the cover over the pan and simmer until the fish flakes easily with a fork and is opaque, about 10 minutes.
Garnish fish with the remaining parsley and serve.