Rinse the quinoa under cold water using a fine mesh strainer to remove any bitterness.
Turn on the Instant Pot and set it to the sauté function. Add olive oil and sauté the diced onion for about 3-4 minutes until it becomes translucent.
Add the minced garlic, and stir for an additional 30 seconds until fragrant.
Stir in the rinsed quinoa, black beans, diced tomatoes (with their juices), corn, vegetable broth, taco seasoning, salt, and pepper.
Close the lid of the Instant Pot securely and set the valve to sealing. Select the manual or pressure cook setting and cook on high pressure for 1 minute.
After the cooking time is complete, allow for a natural pressure release for 10 minutes, then carefully switch the valve to venting to release any remaining pressure.
Open the lid, fluff the quinoa mixture with a fork, and taste to adjust seasoning if necessary.
Serve in bowls and top with your choice of avocado, cilantro, lime wedges, shredded cheese, or salsa as desired.