Start by whisking and setting aside 60 ml of the oil, half the wine, the lemon juice and mustard.
Preheat the oven to the 200 degrees C, air circulation and elements (not grill), rack in the middle.
Take a large rectangular non-stick oven-proof dish and place on the stove on high heat. When hot add the remaining olive oil and a minute later the scallions, peppers, courgettes along with the potatoes and the fennel seeds. Season with 1 teaspoon of salt and the pepper. Reduce the heat to medium and sauté for about 5 minutes. Pour the remaining wine and deglaze for a minute.
Remove from the heat and add the perch fillets on them. Season with the remaining 1 teaspoon of salt, pour all over them the lemon mixture and sprinkle with half of the coriander.
Cook for about 22 minutes while being careful not to dry the fillets. Serve and sprinkle the remaining coriander leaves along with drops of the coriander infused oil next to boiled potatoes.