From a recipe card set of twenty plus years ago it's deliciously different and a great addition to a picnic basket. I've also made this up as a side dish to a meal of baked ham and steamed broccoli. Either way it's a keeper in our family.
Cut tomatoes into strip, about 1/3 in thick. Add to bowl with beans. Add olives and green onion. Fold together carefully.
In a small bowl, whisk together the vinegar and mustard; slowly whisk in the oil until an emulsified mixture is formed. Add salt & pepper and mix well.
Pour dressing over vegetables. Fold together until well blended.
Before serving, garnish with sliced egg and a sprig of parsley if used.