Heat one ounce of olive oil in a 1.5 quart saucepan.  Slice the onion and sautee lightly in the olive oil.
Drain the canned tomatoes (you can use peeled fresh tomatoes if you like) and puree in a blender.
To the pureed tomatoes, add all the spices, thinly sliced Jalapenos, and green olives.  Pour the tomato and spice mixture into the saucepan with the onions and simmer on a very low heat covered for 30 minutes.
While the sauce is cooking, peel and boil the potatoes.
Just before the potatoes are done, heat the remaining olive oil in a large frypan.  Wash and lightly dust the fish pieces in a mixture of flour, salt, and pepper.  Fry the fish, turning once, until just done.
Place the cooked fish in a large platter.  Surround the fish with the boiled potatoes.  Pour the sauce over the fish, sprinkle with chopped parsley, and serve immediately.
Serves 6.