2. Heat the olive oil in a large sauté pan. Add onions, sprinkle lighty with salt and cook over moderate heat until very tender, about 15 to 20 minutes, stirring occasionally. Do not let the onions brown.
3. Add the vinegar and honey and cook for 5 minutes. Add the sun-dried tomatoes, currants, and 4 tablespoons of the mint. Cook for a few minutes longer. Taste for seasoning. You may not need to add additional salt if the tomatoes have been salted, but you will want to add pepper. Adjust the sweet and sour ratio. If you'd like a sweeter taste, add some of the currant soaking liquids. Check again for salt.
4. Sprinkle the fish fillets with salt and pepper and place on to a lightly oiled baking dish. Cover with the onions. Bake for 8 to 10 minutes or until the fish is cooked through. You may need to cook the fish a little longer if the onions were cool when you put them over the fish. Transfer the fish to serving plates and top with the remaining chopped mint.