Turn on the Instant Pot by pressing the “Pressure Cooker/Manual” button and set the timer for 6 minutes on HIGH pressure. Insert the inner pot and add the orange juice, tamari (or coconut aminos), raw honey and mirin. Stir. Add the frozen chicken thighs and spoon some of it on top of the chicken.
Close the lid tightly and move the steam release handle to “Sealing.”
When the timer ends and the Instant Pot beeps, carefully turn the steam release handle to “Venting,” press “Cancel,” and allow the Instant Pot to depressurize quickly until the float valve drops down. Open the lid carefully.
Using tongs, carefully take out the chicken, place them on a cutting board and dice the meat into small pieces. The chicken pieces might be stuck together, but you should be able to cut through them easily. Set the chicken aside. Reserve the cooked liquid in a small bowl.
Add the avocado oil in the inner pot and coat the bottom evenly. Press “Sauté” and when the oil is hot, add the onion and sauté for 1 minute or until it is soft. Add the garlic, celery, carrots, ginger, sea salt, black pepper and orange zest. Stir well.
Add the diced chicken pieces and the reserved cooked liquid back into the inner pot and stir. Press the “Pressure Cooker/Manual” button and set the timer for 10 minutes on HIGH pressure.
Meanwhile, mix the tapioca flour and water in a small bowl to make a slurry and set aside.
When the timer ends and the Instant Pot beeps, press “Cancel” and allow the Instant Pot to cool down naturally for 10 minutes. Then, carefully turn the steam release handle to the “Venting” position for the steam to escape and the float valve to drop down. Press “Cancel,” and then “Sauté.”
Open the lid carefully and stir in the scallions (reserve 1 tablespoon [3 g] for garnish), toasted sesame oil and white pepper. Add the tapioca slurry into the inner pot while stirring for 1 minute or until the sauce thickens. Press “Cancel,” ladle about 1 cup (240 ml) of sauce into a bowl and reserve for serving.
Using a slotted spoon, transfer the chicken into the lettuce wraps, add the garnishes and serve immediately. You can drizzle the reserved sauce, if needed.