Finely dice the green pepper, celery, and scallions. Set to one side.
Add the sour cream, mayonnaise, olive oil, lemon juice, garlic powder, parsley, basil, tarragon, chives, sea salt, and black pepper to a food processor.
Blend the mixture for 20 to 30 seconds. Set the green goddess dressing to one side.
Drain the tuna and add it to a large bowl.
Add the diced green pepper, celery, scallions, and green goddess dressing to the bowl.