Pour 1 cup of water into the Instant Pot® and add the trivet. Place the corn on trivet.
Close the lid; turn the knob to Sealing.
Select the Manual or Pressure Cook button and adjust the time to 3 minutes.
When the timer beeps, immediately turn the knob from Sealing to Venting, then remove the lid and carefully transfer corn to an ice bath.
In a medium bowl, combine the cilantro, lime juice, lemon juice, oil, vinegar, salt, and black pepper. Add beans, green onion, and bell pepper, and stir.
Cut the corn kernels off the cob and gently stir into the bean mixture. Fold in the avocado, transfer to a serving bowl and refrigerate for at least 3 hours before serving.