Wash, boil and peel the potatoes, then cut them into slices or cubes. Cut the radishes into small cubes and the cucumber into small cubes.
For the sauce, mix the soy cream with sunflower oil and 2 to 3 tablespoons of cucumber water until it has a consistency similar to mayonnaise. Season to taste with pepper, salt and agave syrup. Carefully fold in the potatoes and radishes. Cut the chives into fine rolls and pour over them. If necessary, season again with salt and pepper.