- Sprinkle a tablespoon of salt and a few grindings of pepper on the fish. Now coat it well with flour and vigorously remove any excess flour.
- Now heat up oil in a heavy 10 to 12 inch skillet until a light haze forms above it.
- Add some pieces of fish, lower the heat to moderate and brown them 3 to 5 minutes of each side.
- Transfer the browned fish on double thickness of paper towels. Repeat this with all the fish.
- Pour ⅓ of the marinade into a shallow 2-quart enameled, baking dish and arrange half the fish in it in one layer.
- Moisten the fish with ⅓ more of the marinade and arrange the remaining fish in another layer on top.
- Pour in the remaining marinade and let the fish marinade uncovered and unrefrigerated for at least 6 hours.
- Now refrigerate, tightly covered with plastic wrap, for at least 24 hours before serving.
- In a heavy 10- to 12-inch skillet, heat the oil over high heat until a light haze forms above it.
- Drop in the onions, reduce the heat to moderate and, stirring frequently, cook for few minutes until the onions are soft but not brown.
- Stir in the tomato paste, vinegar, sugar, cloves, bay leaf, peppercorns and salt and bring to a boil.
- Cover the pan, reduce the heat to low, and simmer undisturbed for about 15 minutes. Then remove from heat and cool the marinade to lukewarm.