Add your cubed chicken breast to a bowl and toss with the tamari. Set aside to marinate for about 15 minutes.
Preheat your air fryer to 380 degrees Fahrenheit.
Toss the chicken with the cornstarch and breadcrumbs. The breadcrumbs stick a bit more easily if you add them at the same time as the cornstarch.
Add to your air fryer in a single layer. Cook for 10-14 minutes, tossing halfway. How long you need to cook it for just depends on how thick your chicken breasts were. It’s done when the internal temperature reaches 165 Fahrenheit.
While the chicken is cooking, add the minced garlic to a pot with the oil. Saute until lightly golden brown.
Add all remaining ingredients aside from the water and starch and bring to a low simmer.
Whisk together the cornstarch and water and add to the pot with the sauce.
Whisk together and let simmer until thick. Remove from the heat and let cool which will help it thicken further.
When the chicken is done (be sure to cut into the largest piece to ensure it is cooked all the way through) add to a bowl and cool for just a couple of minutes.
Pour half of the sauce on top and toss to combine. This recipe makes quite a bit of sauce, I like to add probably 2/3 of it to the chicken, then reserve the rest for serving.
Serve immediately with steamed broccoli, rice or enjoy as is!