For the salad, clean and wash the leek and cut into fine rings. Rinse the lentils, cover and cook in boiling salted water for about 10 minutes. After approx. 5 minutes add the leek and cook along. Drain the lentils and leek and rinse briefly in cold water.
Coarsely chop the nuts and roast them in a pan without fat until golden brown. Remove. Wash the grapes, pluck them from the stalks, dab dry and cut in half.
For the vinaigrette, mix vinegar, honey, salt, pepper and thyme. Fold in 5 tablespoons of oil. Mix lentils, leek, nuts and grapes with the vinaigrette. Crumble the feta and fold in. Let the salad steep for about 30 minutes.
In the meantime, rinse the fish fillet, dab dry and cut into 4 pieces. Turn in the flour and knock off a little. Heat 2 tablespoons of oil in a coated frying pan. Fry the fish in it over medium heat for 3-4 minutes on each side.
Season with salt and pepper. Season salad with salt and pepper. Arrange everything.