You will prepare the cooking sauce at this point so that it is ready to be placed in the pan at the appropriate time. You will be using the juice from the canned pineapple, so drain the pineapple, in a collander with a bowl beneath it to catch the pineapple juice. Once you have drained the pineapple, measure 3/4 of a cup of the pineapple juice, and pour it into a medium-sized bowl or glass measuring cup. Then, add 1/4 of a cup of soy sauce to the pineapple juice, 1 tablespoon plus one teaspoon of granulated sugar, and 1 tablespoon of rice vinegar. Stir in 1/4 teaspoon of crushed red pepper, and 2 tablespoons of corn starch. Stir the mixture well with a wire whisk until it becomes smooth. Set the sauce aside until it is ready to be added to the chicken.