Tuna Sourdough Sub Sandwiches

1 12-oz can chunk light tuna in water - drained
1/2 cup diced celery
1 small apple, diced
1/4 cup raisins (optional)
1/4 cup mayo
1/2 tsp. onion powder
1/4 tsp. dry mustard
4 sourdough sandwich rolls, cut in half

optional:
lettuce, tomato, onion, Dijon mustard

Combine tuna, celery, apple, and raisins in medium bowl; mix well.  Combine mayo, onion powder, and dry mustard in small bowl; mix well.  Add to tuna mixture and toss until coated.  Divide tuna mixture and spoon onto 4 sourdough bread halves.  Garnish with lettuce, tomatoes, Dijon and onions as desired. 

Serves 4.  Taken from The Busy Mom's Make It Quick Cookbook