Rinse fish in cold water, pat dry with paper towel and set aside. In a small bowl, combine together with a fork, paprika, celery powder, garlic powder, onion powder, salt, pepper and thyme. Add the rub to both sides of the fish pieces.
In a cast iron pan or medium skillet, melt butter over medium-high heat and pan-sear the fish on both sides, about 3-4 minutes on each side. Carefully, remove the fish from pan and transfer to a plate.
Add olive oil to the pan, sauté the onions for 3-4 minutes, then add peppers and sauté for a couple of minutes, then stir in the tomatoes. Reduce the heat to simmer, and place a lid on the pan. Cook for about 15 minutes, long enough for the tomatoes to burst, stirring occasionally. Season with sugar, salt and pepper. In a small bowl, add the flour and about a tablespoon of water, stir until blended and add to the tomato sauce, stirring until you notice it starts to thicken slightly.
While the tomato stew is cooking, preheat oven to 425°F. Return the fish back into the pan. Combine the bread crumbs with the lemon zest and sprinkle over the fish. Then place the pan into the oven for 2-3 minutes, long enough for the bread crumbs to become crispy.
Garnish with fresh thyme or parsley. Serve as is or with rice or mashed potatoes. Enjoy!