1-In a bowl put the parsley and cilantro add the lemon juice, Harissa ,garlic ,tomato paste ,salt ,pepper, cumin ,paprika and mix all the ingredients to get a beautiful sauce.
2-Marinate your fish with some of the sauce and preferably leave it for 45 to 60 minutes to absorb the sauce.
3-Take your Tagin or your glass oven pan and put your onion (some people do not use onions) as a first layer then add your carrots, potatoes, poor the rest of your sauce to your vegetables, add your whole fish and top it with the green and red peppers, tomatoes and lemons, add the vegetable oil as needed and cover your Tagin or wrap your oven pan with the aluminum foil and bake it in 350 degrees for 45 minutes.
4- If you are cooking this dish in your oven pan, uncover it and let it for another 10 minutes to have less juice and to give a nice color to your top veggies, or cook it in a medium heat in Tagin (usually the clay absorb the water, so if you need some juice just add some water from time to time) for 45 minutes
Serve your Tajin hot as a main dish with Moroccan homemade bread, or French bread and enjoy the deliciousness.