Method
Bring a pot of water to a rapid boil. Add the elbow macaroni and stir. Return to a boil and stir. Cook 10-12 minutes or until tender. Drain the macaroni and rinse under cold water. Drain and chill while preparing the remaining ingredients.
Drain the water from the tuna and place the tuna in a bowl. Add the scallions, red bell pepper, celery, dill, lemon juice, horse radish, Dijon mustard, salt and black pepper. Stir to blend well. Add the elbow macaroni and mayonnaise. Gently stir to blend well.
Chill and serve cold.