1. Dissolve the chicken stock cube in the water and add the trimmed green beans.
2. Boil for about 10 minutes (they should still be fairly crisp).
3. Drain and rinse briefly under cold water.
4. Arrange in a shallow bowl and pour over the French dressing while the beans are still warm (This ensures the beans soak up the dressing).
5. Leave to cool completely.
6. Arrange the sliced tomato and onion around the edge of the bowl and garnish with whole or chopped black olives, if desired.