Prep the chicken: Slice the chicken breast into very fine slivers. Place the slivers in a bowl and sprinkle baking soda over the top. Toss the chicken in the baking soda and allow it to marinate for 20 minutes. This is called velveting the chicken and it creates a very delicate soft texture. Once the chicken has marinated for 20 to 25 minutes, rinse it thoroughly with water and place the chicken in a colander to drain.
Chop the Vegetables: Meanwhile, chop the vegetables for the stir-fry and place them in separate piles on a cutting board. Chop the onions and bell peppers into 1-inch pieces. Slice the carrots and celery into thin slices on a bias, so they are elongated. Mince the garlic. Drain the water chestnuts.
Make the Sauce: Set out a measuring pitcher (or mixing bowl) for the sauce. Combine the chicken broth, soy sauce, cooking sherry, cornstarch, and sugar. Mix well and set aside.
Stir Fry: Once all the ingredients are prepped, and the chicken is rinsed and well-drained, set a large deep cast iron sauté pan, or a large wok, over high heat. Set a baking dish to the side of the pan as a holding plate for the vegetables. One veggie at a time, drizzle a teaspoon of sesame oil in the hot pan, and quickly stir fry the vegetables for 1 to 2 minutes, just long enough to get chard around the edges but not cooked through. You want the vegetables to still be quite firm. Do this in small quick batches so the vegetables sear and not steam. Then move the stir-fried vegetables to the holding plate and repeat.
Once all the vegetables are stir-fried and in the holding plate. Add 2 teaspoons of sesame oil to the skillet. Add the drained chicken pieces and minced garlic to the pan. Stir fry for 3-4 minutes to sear the chicken.
Once the chicken is mostly cooked, pour in the water chestnuts and sauce mixture. Bring the sauce to a simmer and cook for an additional 3-4 minutes until the sauce tightens into a thick gravy consistency.
Add all the vegetables to the pan and stir to coat in sauce. Stir and cook for another 1-2 minutes to rewarm the vegetables, being careful not to overcook them. Then turn off the heat and serve.
Serve over steamed rice, fried rice, over noodles, or as-is for a lower carb dish.
