Step 1

Select SAUTÉ setting on a programmable pressure multicooker (such as Instant Pot). (Times, instructions, and settings may vary according to cooker brand or model.) Select HIGH temperature setting; add 1 tablespoon of the oil to cooker, and allow to preheat 2 to 3 minutes.

Step 2

Season chicken pieces with salt and pepper. Add half of chicken to cooker; cook until browned, 3 to 4 minutes per side. Transfer chicken to a plate; add remaining 1 tablespoon oil and chicken to cooker, and cook until browned, 3 to 4 minutes per side. Transfer chicken to plate.

Step 3

Add onion, celery, and carrots to cooker, and cook, stirring occasionally, until onion is translucent, 4 to 5 minutes. Add garlic to cooker, and cook until fragrant, about 1 minute. Press CANCEL.

Step 4

Return chicken to cooker; add 4 cups of the stock. Cover cooker with lid, and lock in place. Turn steam release handle to SEALING position. Select MANUAL/PRESSURE COOK setting. Select HIGH pressure for 5 minutes. (It will take 10 to 12 minutes for cooker to come up to pressure before cooking begins.)

Step 5

Carefully turn steam release handle to VENTING position, and let steam fully escape (float valve will drop). (This will take 4 to 6 minutes.) Press CANCEL.

Step 6

Remove lid from cooker. Remove chicken from cooker; let rest 5 minutes, and shred.

Step 7

Meanwhile, add noodles and remaining 4 cups stock to cooker. Select SAUTÉ and HIGH temperature setting; cover cooker with lid, and lock in place. Cook noodles and stock for 8 minutes. Carefully remove lid, and stir in lemon juice, parsley, and shredded chicken.