Roll in cornstarch until well coated. (Baking dish works well for this.)
Dip in egg whites to coat.
Mix together pecans, brown sugar, salt, and allspice.
Empty out the corn starch from the dish then spread ½ the nut mixture in bottom of dish. Place tenderloin filet in and gently roll. Sprinkle and pat remaining mixture on wherever coating isn't adhering, until fully encrusted.
Oil & Preheat grill. Reduce to medium heat. Roll the filet out onto grill (picking up might make the crust stick to fingers or utensils ).
Put the cover down and grill for 5 minutes, then roll over. Total cook time will be 15-25 minutes depending on the size of filet and how hot your grill runs. You are looking for an internal temperature of 145-160 degrees. (I typically cook them to 150-155 degrees, but the one pictured went to 160 degrees).
Allow the meat to rest after removing from the heat for 8-10 minutes, before slicing.
Nutrition calculated on 1 ½ pounds of pork with assumption about ½ of the cornstarch adheres to pork.