Cut the cucumber into medium cubes. Put the beans in a colander and rinse with cold boiled water.
Mix all the ingredients for the dressing: salt, black pepper, vinegar, garlic (pass through the press), vegetable oil, sugar and coriander. Let stand for 5 minutes. Stir again before serving the salad.
Sprinkle the sesame seeds on the salad, pour the dressing over it, mix and serve immediately.