In a large pot, bring 4 quarts of water to a boil. Add sea salt and pasta, and let cook, stirring often, until just tender. While the pasta is cooking place the drained tuna into a large bowl and flake with a fork. Drain the pasta when al dente, and rinse with cold water until it's cool, then drain shortly. You want the pasta to still be slightly wet. Place it into a large bowl.

In a small bowl, mix together the mayo and yogurt, dijon mustard, onion, celery, lemon juice, parsley, garlic powder and cayenne powder, then give it a couple of minutes to absorb the flavors. Add the sauce to the pasta and tuna and gently mix to combine. Let sit until the texture of the salad is no longer watery, about 5-10 minutes. Season to taste with sea salt, then serve.