Cut the tips of the chicory 2 cm wide and rinse, use the rest elsewhere. Rinse fennel, cut into quarters and finely slice, chop fennel greens. Rinse thyme, shake dry and also chop finely. Peel the garlic, as well as the onions. Cut garlic into fine slices and onions into narrow wedges.
Rinse cooled fish fillet, rub dry and make a few even incisions on the skin side with a sharp kitchen knife. Divide fish into four equal pieces, season with salt, pepper, juice of one lemon and fennel seeds. Then turn in flour to the other side. Heat cooking oil in a fireproof frying pan and place the fish fillets skin side up in the frying pan and sear until hot. Next, turn to the other side and place the fish, skin side down, in the roasting pan in the preheated oven, roast on the first rack from the bottom at 180 degrees for 6 to 8 min.
Heat the olive oil in another frying pan and roast the onion and fennel for about 5 to 6 minutes, turning occasionally to the other side. Then add the chicory tops, thyme and garlic and fry for about 1 minute more. Extinguish with orange juice and wine and steam open for 5 minutes. Stir cold butter cubes and fennel greens into the vegetables and let them bubble up once. Season to taste with salt and freshly ground pepper. Transfer vegetables to a serving platter Fo