12 to 16 ounces firm white fish fillet, cut in 3 to 4-ounce portions
1/2 teaspoon anchovy paste
3 tablespoons dried breadcrumbs
3 or 4 sprigs fresh, flat-leaf parsley
8 to 10 fresh mint leaves
3 or 4 large fresh basil leaves
Salt and freshly ground pepper to taste
1/2 cup dry white wine or water
10 to 12 oil-cured black olives, cracked and pitted
Preheat the oven to 200c (400°F.)
Cut the onion into quarters, then cut the quarters crosswise and separate the layers to create wide, square slices. In a sauté pan, heat 1 tablespoon of olive and add the onion. Season with salt and pepper, and sauté over low heat until the onion has wilted and started to turn translucent; be careful not to let it brown. Add the red wine vinegar to the pan and shake it briefly, then transfer everything to the bottom of a medium-sized baking dish.
Wipe the pan with a paper towel to clean it, then place it back over low heat and add the remaining tablespoon of olive oil. Add the anchovy paste and stir with a wooden spoon to dissolve the paste into the oil. Dump the breadcrumbs into the pan and stir to completely coat them with the oil. Transfer the breadcrumbs to a small bowl to cool slightly.
Wash the herbs, pat them dry, and finely chop them. Add them to the bowl with breadcrumbs, and season everything with a small pinch of salt and a few grinds of black pepper.
Lay the portioned fish on top of the onions and season with a bit more salt and pepper. Distribute the breadcrumb-herb mixture evenly on top of the fish. Add the white wine or water to the pan and scatter the olives around the dish.
Bake the fish for 15 to 20 minutes, depending on the thickness of the fish; it should be cooked through but still moist; check the pan after 10 minutes and add a bit more water or wine if necessary.
Serve immediately, with the some of the onions, olives and pan juices spooned alongside the fish.
