For Tuna and Green Bean Salad:
Top and tail the green beans. Blanch in boiling salted water and refresh in ice water. Drain and set aside.
Quarter the cherry tomatoes. Cut the spring onions into batons. Cut the black olives into half. Flake the tuna fish.
Mix all the ingredients in a bowl.
For the dressing:
In a food processor add the boiled egg, salt, pepper, olive oil, and white wine vinegar. Blend well and pour over the salad. Toss, chill and serve.