In an electric pressure cooker combine the chicken breasts, onions, coconut milk, curry paste, coconut aminos, fish sauce, ginger, sea salt, and black pepper and stir with a spoon.
Place the lid on the pressure cooker. Make sure the vent valve is in the SEALING position. Select the MANUAL/PRESSURE COOK function and HIGH PRESSURE. Use the +/- buttons until the display reads 30 minutes.
When the cooker beeps to let you know it's finished, wait until the display panel reads, LO: 05. Switch the vent valve from the SEALING to the VENTING position, use caution while the steam escapes, it's hot.
Carefully remove the chicken breasts from the pot and set on a cutting board. Stir in the stir-fry vegetables, the residual heat should cook them. Select the sauté function to warm them further, if needed. Cut the chicken breasts into cubes and stir back into the vegetable curry mixture.
If using frozen chicken breasts, cook for 40 minutes.