Bring a large pot of water to a boil for the pasta. Salt water and cook pasta to less than al dente, 5-6 minutes. Drain and drizzle with a touch of oil to keep pasta loose.
In a large bowl, flake tuna and add herbs (reserving a tablespoon or 2 to mix with the breadcrumbs). Add onions and celery; dress with lemon juice and 3 tablespoons EVOO and Dijon mustard. Season with salt and pepper to taste. Add pasta and combine well, transfer to baking dish or large casserole.