Add the sauce ingredients to the Instant Pot: soy sauce, water, rice wine vinegar, ginger, garlic, sugar, sesame oil, and white or black pepper.
Next, add the shrimp, onion, zucchini, and mushrooms.
Cover with the lid, ensuring that the valve is in the sealing position. Press on the manual or pressure cook setting, and cook on LOW for 0 minutes.
Once the cooking is finished, quickly release the steam and carefully remove the lid.
If the sauce is not thick enough, either remove the vegetables or leave them in. Then add the slurry, which is 1 tablespoon of cornstarch mixed with 1 tablespoon of water. Cook on the sauté setting for 1 minute, and return the veggies after the sauce is thickened.
Serve over rice and garnish with toasted sesame seeds and chopped green onion or parsley.