1. Heat a non-stick pan over medium-high heat. Coat pan with coking spray. Gently add the fish and cook for 5 minutes on each side or until fish flakes easily with a fork. Set aside.
2. Heat oil in a non-stick pan, add the sliced onions, cook for 4 minutes or until soft. Add the garlic, oregano and tomatoes. Bring to a boil, reduce heat and simmer for about 5 minutes, stirring frequently. Add the olives and capers.
3. Place the flounder on a plate, spoon the tomato mixture over the fish.
4. Garnish with chopped parsley.
* Grouper can be used in place of the flounder.
** Green, Greek or whatever olives are handy can be used in place of kalamata olives.