1. Combine the soy sauce, sherry, and water in a medium bowl; add the chicken and stir to break up the clumps. Cover with plastic wrap and refrigerate at least 20 minutes or up to 1 hour.
2. Mix the sesame oil, cornstarch, and flour together in a medium bowl until smooth. Drain the chicken in a mesh strainer. Toss the chicken in the cornstarch-flour mixture until even coated. Use immediately in a stir-fry recipe.