In a medium hot pan saute the onions with the capers in 2 tablespoons of olive oil. Cover and turn heat down to medium heat and let simmer for about 20 minutes stirring occasionally with a wooden spoon. Add the thyme about 10 minutes into the cooking of the onions. Adjust the seasonings with salt and pepper. Stir in the quartered tomatoes and let simmer for 10 minutes more. Slice the zucchini into thin discs. In a hot saute pan heat 1 tablespoon of olive oil and saute the zucchini in the oil. Add salt and pepper as needed. In a medium hot saute pan heat 1 tablespoon olive oil and saute the fish gently, crisping the skin, Turn the fish over and let the temperature of the pan finish the cooking of the fish. To assemble the dish, lay the zucchini around in a small pile on the bottom of the plate, place the fish on top of that. On top of the fish place a small amount of the tomato and onion sauce. Garnish with olive oil and fresh chives.