Place potatoes with skin on in a steamer rack over boiling water and steam until tender. Then steam the carrots, peas and chicken breast until tender. Let them cool. (if you don't have a steamer rack, boil the vegetables and chicken until tender)

Peel the potatoes and chop them in small pieces. Chop the carrots, cucumbers and chicken breast also in small pieces. Combine them with potatoes and peas in a large salad bowl. Add salt and freshly-ground black pepper, to taste and mix carefully.

Prepare the mayonnaise. Using a mixer, beat yolks and mustard, in a small bowl until thick. Gradually add oil beating all the while. When ready gently fold in to vegetables. Pour all mixture in the serving dish. Garnish with black olives and serve with crackers.