Whisk yogurt, mayonnaise, lemon, Dijon, oil, honey, garlic, dill, salt and pepper; reserve one-third in a covered container.
Boil pasta in salted water according to its package, beginning checks 2 minutes early.
Rinse briefly under cool water, drain very well and spread on a towel-lined tray for 5 to 10 minutes.
Flake well-drained tuna into large pieces and pat celery, cucumber and peas dry.
Fold pasta, tuna, vegetables, scallions and herbs gently with two-thirds of the dressing.
Chill 1 hour, fold in reserved dressing as needed and divide among six containers.