In a large pot or dutch oven combine 2 cans water chestnuts, 2 cans bean sprouts, 8 cups shredded carrots, 4 cups chopped celery, 4 cups chopped green onions, and 4 tbs minced garlic. Cook until above-listed ingredients are softened, then mix in precooked shredded chicken.
In a separate mixing bowl whisk together 5 tbsp cornstarch, 5 tbsp soy sauce, 5 tbsp Sesame oil, 2 tbsp ginger paste (or powder), 5 tbsp water, and 2 tbsp olive oil.
Once step 2 is completely mixed add to chicken and vegetable pot, bring to gentle boil and stirring often.
Fill each egg roll wrapper with about 2 tablespoons of the completed chicken and vegetable mixture. Wrap gently and place on non-stick sprayed baking sheet.
Preheat oven to 415 degrees. Bake egg rolls for 15 to 20 minutes, until brown and crispy.