Cover the potatoes in a saucepan with water, salt lightly and bring the water to a boil. Cook the 1 kg potatoes over medium-high heat for about 20-30 minutes.
After the cooking time, try whether the potatoes slip off the fork easily when you poke them. Then drain the water and let the potatoes cool down a bit so that you can peel them easily.
In the meantime, peel the ½ onion and cut into fine cubes. Boil the 1 tbsp soup seasoning with the 100 ml water in a pan and sauté the onions for about 3 minutes until they are translucent.
Peel the slightly cooled potatoes and cut into thin slices.
In a salad bowl, mix the sauteed onions with the potato slices. Add 1 tsp salt, 1 tbsp lemon juice and 2 tbsp linseed oil and mix well. Leave in the fridge for at least 1-2 hours.