Heat ½ cup of the olive oil in a large casserole or Dutch oven over medium heat and cook the onions, stirring, until wilted, about 10 minutes. Add the garlic and stir for a minute, Add the diluted tomato paste, raisins, and spices. Pour in the wine and add the thyme sprigs. Reduce the heat to medium-low and simmer the onions, covered, for 15 to 20 minutes, until very tender.

Cut the cod or other fish into large chunks. Place the fish on top, cover and simmer until the fish is flaky and fork-tender, another 15 to 20 minutes.Serve immediately, drizzled if desired with remaining olive oil.