Combine lime juice, coriander seed, ground ginger, cardamom, butter, salt and white pepper; blend well.
Coat sable fillet and marinate for 4 hours in the refrigerator.
Roast Sable at 400° F for five minutes. Let cool, then cut into strips 1/2-inch wide by the length of the fillet.
Roast peppers and onion at 400° F. until some peppers begin to blacken. Let cool.
Add mango and combine with sable.
Blanch lemon, then zest and add to the combination of sable, mango, and pepper mixtures; toss lightly to mix.
Rinse spinach and blanch; dry with clean towel.
Combine spinach, Parmesan cheese, egg whites, panko; set aside.
Place 1 sheet of filo on a piece of plastic wrap, lightly brush with softened unsalted butter, placing more on the edges.
Sprinkle with Parmesan cheese, repeat five times.
Evenly spread/arrange the spinach mixture on the filo except for the outer one inch. Place two more sheets of filo on top and oil the edges. Place the sable mixture on top except for one inch around the edges.
Roll the entire sheet into a log shape, then sprinkle with Parmesan cheese.
Bake at 400°F until golden brown.
Let stand for 10-15 minutes. Cut strudel and serve.