Pour water into Instant Pot® and add the trivet. Place corn on trivet.
Close the lid; turn the knob to Sealing.
Press Manual or Pressure Cook button and adjust 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 cilantro, lime juice, lemon juice, oil, vinegar, salt, and black pepper. Add beans, green onion, and bell pepper, and stir.
Cut corn kernels off the cob and gently stir into bean mixture. Fold in avocado, transfer to a serving bowl and refrigerate at least 3 hours before serving.