Slice the chicken: Hold your knife at a 45-degree angle to make each slice wider and flatter. Slice against the grain into thin pieces (about ⅛-inch thick).
Marinate the chicken: In a medium bowl, combine the chicken with the soy sauce, black pepper, salt, olive oil, starch, and baking soda. Mix well. Set aside in the fridge to marinate for 15 minutes.
Dice the vegetables: Roll cut the zucchini and yellow squash into triangle-like chunks, about ½ inch at the widest point. Keep pieces about the same size so they cook evenly.
Chop the aromatics: Finely mince the garlic, julienne the ginger, and slice the scallions into small rounds. Separate the white and green parts and place them together in one bowl.
Combine the sauce: In a measuring cup, combine all the stir-fry sauce ingredients from vinegar to ginger. Stir well.
To stir fry the chicken: Preheat a large sauté pan or wok over medium heat until it’s too hot to hold your palm 2–3 inches above the surface.
Add 1.5 tbsp oil and swirl it around the pan. Add the chicken, turn heat up to medium-high, and quickly spread it into a single layer. Pan fry without stirring until golden brown, about 2–3 minutes.
Use a spatula with a firm edge to flip the chicken and sear the second side, about 1–2 minutes, until cooked through and golden on the outside. Transfer to a plate.
Sauté the aromatics: In the same pan, add 1 tbsp oil. Sauté the garlic, ginger, and pale green scallion parts over medium heat until fragrant, about 8–10 seconds.
Add vegetables: Turn heat to medium-high. Add zucchini and squash. Season with 2 pinches of salt. Stir-fry for about 2 minutes, tossing often, until the squash softens but still has a light crunch.
Return chicken and add sauce: Return the chicken to the pan. Stir the sauce again, then pour it in. Toss everything together for 30 seconds to 1 minute until the sauce thickens.
Serve: Turn off the heat. Taste and adjust salt if needed. Garnish with green scallion parts and a small drizzle of sesame oil. Serve hot or warm with rice.
Notes
Make-ahead and storage: Slice and marinate the chicken ahead of time. For a quick marinade, 20–30 minutes is enough. Or refrigerate and cook within 1–2 days.
To freeze: Place the marinated chicken in a freezer-safe bag, lay it flat, and freeze for up to 2 months. Defrost overnight in the fridge before stir-frying.
Coconut aminos to light soy sauce conversion: 1 tbsp coconut aminos ≈ ½ tbsp light soy sauce + ½ tbsp chicken stock + ¼ tsp coconut brown sugar.
To substitute soy sauce with coconut aminos in this recipe: Use 1 tbsp coconut aminos in the chicken marinade and 3 tbsp in the stir-fry sauce (omit the sugar and reduce chicken stock to 2 tbsp).
What is a roll cut and why use it: A roll cut means cutting the vegetable at an angle, then rolling it a quarter turn before the next cut. This creates chunky, irregular shapes with more surface area, so the pieces cook evenly and soak up more sauce without turning mushy.