• Gather all the ingredients.
  

To Mix the Sauce

• Add 1 Tbsp soy sauce, 1 Tbsp mirin, and ¾ cup water in a medium bowl; I used a measuring cup with spout and handle for easy pouring. Add the 1 Tbsp oyster sauce and stir to combine.
  

To Prepare the Vegetables and Slurry

• Cut 1 head Shanghai bok choy lengthwise into quarters. Cut them crosswise into bite-sized pieces about 2 inches (5 cm) long. Keep the thick white stems and leafy greens in separate piles.
  
• Peel 1 inch ginger and cut lengthwise into thin slices. To make the slurry, add 1 tsp potato starch or cornstarch and 2 tsp water to a small bowl and mix until smooth.
  

To Prepare the Chicken

• Slice 1 boneless, skinless chicken breast into 1½-inch (4 cm) squares of equal thickness. Sprinkle ¼ tsp Diamond Crystal kosher salt and ⅛ tsp freshly ground black pepper on both sides. Nami's Tip: I tilt my knife back and slice the chicken at an angle using the sogigiri Japanese cutting technique. This creates thinner, flatter pieces with an open surface area so the chicken cooks evenly and at the same rate in the frying pan.
  
• Transfer to a shallow tray and sprinkle with 2 Tbsp potato starch or cornstarch. I use my favorite stainless prep tray.
  
• Dust the chicken all over with the potato starch. I close the lid on the tray and shake everything together for the perfect light coating.
  

To Cook

• Preheat a wok, frying pan, or saucepan (I used my All-Clad 2-QT Copper Core Saucepan) over medium heat. When it's hot, add 1 Tbsp toasted sesame oil. Once the oil is hot, add the chicken in a single layer, leaving space between each piece. Cook the first side for about 3 minutes. Nami's Tip: I cook in two batches to avoid overcrowding the pan. This helps the chicken sear evenly and develop a nice crust.
  
• When the chicken is slightly brown on the bottom, flip it over and sear the other side for 2 minutes. (If your pieces are thick, I recommend covering with a lid and cooking for 3 minutes.) Remove to a prep tray or plate.
  
• Repeat searing the remaining chicken. Nami's Tip: Make sure that the chicken is nearly cooked through at this stage. You will only cook it briefly at the end when tossing with the sauce.
  
• Once both batches are done, add all the chicken back into the pan. Next, add the ginger and the thick bok choy stems.
  

To Add the Sauce

• Toss together to heat. When the thick parts have softened a bit, add the bok choy leaves. Then, add the sauce and stir to combine.
  
• Toss to coat the ingredients in the sauce. Bring the sauce to a simmer.
  
• When it's simmering, give the slurry a final stir and pour it into the pan. Stir thoroughly as you bring the sauce back to a simmer.
  

To Serve

• Turn off the heat once the sauce has thickened. Serve on individual plates; I used a White Wave Whale Pasta Bowl from JOC Goods.
  

To Store

• I recommend transferring the leftovers to an airtight container. You can store it in the fridge for up to 3 days and in the freezer for a month.