Boil lentils, strain, refresh with cold water and drain. Wash zucchini and cut into small cubes.
Heat 1 tbsp. olive oil in a pan and sauté the zucchini cubes over medium heat about 2 minutes. Add sugar and sauté some minutes more.
Deglaze with balsamic vinegar, fold in lentils, and pour all into a bowl and let cool. Wash spring onions and cut into thin rings. Wash tomatoes and cut into quarters.
Both fold with the remaining olive in lentils and season with salt and pepper. Marinade the salad about 30 minutes in the refrigerator.
Divide trout fillets into pieces. Serve lentil salad on plates or in glasses and put smoked trout top.

Variants: any kind of smoked fish, ham, small mozzarella balls, carrot strips