Chicken tenderloin is the healthiest and easiest part of the chicken to make into a stir-fry. I flavored it with black bean sauce, but you can easily adapt the recipe with your favorite stir-fry sauce. See the recipe notes at the bottom if you need to make some substitutions.
If you are using fermented black beans, rinse and drain the beans and then coarsely chop. Coarsely chop 1 clove garlic and add to the chopped black beans and mince to combine.
If you are not using black bean sauce, you can substitute with hoisin sauce and add it into the stir-fry in the middle at step 6. If using any kind of Asian sauce with sugar in it (sweet and sour, orange sauce, etc.) add it at the end at step 7 and cook until warmed through and the chicken is thoroughly coated.