Add 1/4 cup (59 ml) low-sodium soy sauce, 1 tablespoon (13 g) brown sugar, 1 cup (237 ml) low-sodium chicken stock, and 1/4 teaspoon pepper to the insert of the Instant Pot. Stir until the brown sugar is mostly dissolved.
Place 1 pound thawed chicken breasts in a single layer into the liquid, pressing them down so they are at least partially submerged.
Close the lid and turn the pressure valve to SEALING. Select the "Poultry" setting on high pressure for 10 minutes. (If your cooker has no Poultry button, use Manual/Pressure Cook on HIGH for 10 minutes.)
When the cook time finishes, allow the pressure to release naturally for 5 minutes, then carefully move the valve to VENTING to quick-release any remaining pressure. Wait until the float valve drops and the lid can be opened safely.
Remove the chicken from the pot to a cutting board, slice or shred as desired, spoon some of the cooking sauce over the chicken, and serve.
Notes
Recipe Notes
Make sauce for the chicken: remove the chicken from the sauce. Mix 1 tablespoon cornstarch with 1 teaspoon water. Turn the instant pot to sauté and add the cornstarch mixture. Cook, stirring, until it boils and thickens.