Add the sauce ingredients to a small bowl and whisk together.
Cut the chicken into about 1" pieces and add it to another bowl. Add the garlic powder and pepper and stir until coated, then add the cornstarch and stir again to coat.
Add 2 tablespoons of oil to a skillet. Let it heat for a few minutes over medium-high heat. Cook the chicken in 2 batches (don't crowd the pan). Cook the chicken for 4 minutes and then flip (I use tongs to make it easy) and cook for another 3-4 minutes or so. Chicken should be browned and cooked through (165F). Transfer chicken to plate. For the second batch, I add another tablespoon of olive oil to the pan.
Once the second batch of chicken is done, add the chicken that's on the plate back to the pan. Stir in the sauce and let it bubble for a minute or so, until thickened. Serve immediately over rice with scallions & sesame seeds sprinkled on top.
Mirin is a sweet Japanese rice wine. For this recipe, it's fine to use the grocery store version (found in the Asian foods aisle near soy sauce etc.). I use Kikkoman brand.
Handy trick: the ginger is much easier to grate if it's frozen. I always keep some fresh ginger in the freezer and I use my Microplane grater/zester to easily grate it.
Nutritional information is provided as a courtesy only and should be construed as an estimate rather than a guarantee. Ingredients can vary and Salt & Lavender makes no guarantees to the accuracy of this information.