Bring a large pot of water to a boil, and salt the water generously. Cook the pasta according to package directions, drain, and rinse with cool water.
Meanwhile, in a food processor or blender, combine the cilantro leaves, shallots, and Dijon. Puree, add the mayonnaise and yogurt, if using, cream, salt, pepper, and cayenne and puree. Taste and adjust seasonings.
In a large bowl, combine the pasta, cilantro sauce, and salmon pieces, and toss gently to combine well. Garnish with additional cilantro leaves, if desired, and serve.
You can use any kind of cooked salmon, grilled, baked, broiled, or poached.