Make sure the stainless steel insert is in your Instant Pot. Press saute setting. Add oil to pot and heat it up. Add minced garlic, onion and pepper. Saute for 1 to 2 minutes. Add butter and saute until the onion is translucent. Press "cancel/off" button.
Add corn and beans to Instant Pot and stir well. Sprinkle taco seasoning, salt and pepper. Add quinoa and water and stir everything together.
Add diced tomatoes (with liquid) in the center, on top of other ingredients. DO NOT STIR.
Close the lid, switch the valve to sealing position. Make sure the IP is set to cook at HIGH pressure. Set timer to 1 minute. The Instant Pot will beep and start coming to pressure.
Once the timer is done, press "cancel/off" button. Let the pressure release naturally. Open the lid away from your face and stir quinoa.
Serve with shredded cheese, chopped red onion, cilantro, avocado and lime wedges.
Notes
For meal prep: cook Mexican quinoa according to instructions above. Cool completely, then divide into meal prep containers. Store in fridge for up to 5 days.