In a small bowl, stir together rice vinegar, sugar or stevia, soy sauce, and ½ teaspoon sesame oil until combined.
In another bowl, dissolve the cornstarch into the water.
Heat 2 Tbsp sesame oil over medium heat in a saucepan. Add and stir minced garlic and cookuntil fragrant (around 30 seconds).
Re-stir the sauce, add it to the saucepan and bring to a boil, stirring often.
Re-stir the cornstarch- water mixture and add it to the sauce a little at a time (stirring as to combine) until it is a desired thickness. The longer it heats up the thicker it will get. If you prefer a thinner sauce, cook less or use less of the cornstarch-water mixture
Set aside until ready to use.
In a large skillet, over medium high heat, add 2-3 tbsp sesame oil and heat until shimmering but not burning. Add chicken and cook until no longer pink. Remove from skillet and set aside.
To the same skillet, add extra oil, if needed. Add peppers, squash, beans, and eggplant, stirring often. Cook until tender, about 8 minutes. The longer you cook the vegetables, the softer the become.
Add bok choy and saute until wilted and tender, about 1-2 minutes.
Add cooked chicken, stir to combine.
Add the garlic sauce to the sauteed vegetables and stir to combine. Heat 2-3 minutes until warm.