Take the fish out of the fridge and let it reach room temperature. Then peel the carrots and finely dice them with the celery. Clean the leek and cut it into fine rings, then put the vegetables in a saucepan and let them sweat on the stove. As soon as the vegetables are sweaty, add the lentils and lemon zest. Mix the broth with the orange juice and add to the lentils in the saucepan. Cook everything until the lentils are done, which takes about 15-25 minutes, depending on the type of lentil. While the lentils are simmering, the lemons are peeled. To do this, cut off the skin with a knife, then remove the fillets (see video) and squeeze out the empty lemon skins. Catch the juice in the process. Drizzle the fish with the lemon juice and pepper and salt on both sides. As soon as the lentils are ready, melt the butter in a pan, add the cinnamon stick and fry the fish on both sides until it is done. Meanwhile, the lentils should be seasoned with cream and seasoned. Add the lemon fillets to the lentils, remove the lemon zest. Season to taste with salt and pepper. Arrange everything on a plate, place the fish fillet on the lentils and garnish with the lemon zest.