Swiss Chard Tuna Salad

This recipe was sent to me by Adriana via Farmgirl Fare , I made it sunday. It is really nice. I used fresh dill and sandwich rolls that we picked up at the farmers market. It was lite and a perfect use of all the swiss chard we seem to be growing in Wrigley. I used the golden chard, to me that is the best to eat raw and the stems are tender and crisp.

1/2 cup mayonnaise
1 teaspoon dijon mustard
2 teaspoons balsamic vinegar (I like white balsamic)
1/4 cup chopped kalamata olives (about 10 olives)
2 teaspoons brine from the olives (or more balsamic vinegar)
2 6-ounce cans tuna (oil or water packed), drained
3/4 cups chopped Swiss chard stems
2 to 3 cups chopped Swiss chard leaves
1/4 cup loosely packed chopped fresh parsley, preferably Italian flat leaf
1 cup (or more) chopped scallons
Salt & pepper to taste