Rinse 1 cup quinoa in a fine-mesh strainer. (This will help take the bitterness out of the quinoa’s outer coating.)
Pour quinoa into a small saucepan with 1 ¾ cups of water and ½ teaspoon of salt.
When the water comes to a boil, turn down the heat to medium-low, cover pot, and simmer for 15-20 minutes, or until the liquid has evaporated. Let it sit for 5 minutes and then uncover it and fluff with a fork.
Put quinoa into a large bowl and let cool to room temperature.
While quinoa is simmering, prep the rest of your ingredients by finely chopping the red onion and rinsing the corn kernels (if using canned corn).
Cut avocados in half lengthwise around the pit, then make a cross-hatch pattern with your knife in the flesh. Scoop out the diced avocado.
To make the vinaigrette, whisk together the lime juice, olive oil, salt, pepper, and chopped cilantro.
To assemble the salad, add the vinaigrette to the bowl with the quinoa and stir.
Stir in red onion and corn kernels.
Reserve some of the avocado chunks and feta crumbles to use as a garnish.
Stir in the rest of the feta, then gently fold in the rest of the avocado.
To serve, scoop quinoa salad onto plates or bowls and garnish with a few avocado chunks, feta crumbles, and chopped cilantro. Serve with lime wedges.
Notes
Make-Ahead Instructions: The only issue with making this salad in advance is the avocado. Avocado browns quickly after it is peeled. However, the rest of this salad can be made in advance, and stored in the refrigerator for a few days. If you want to make the salad in advance, prepare everything except the avocado, then peel and cube your avocado and fold in gently just before serving. Using Fresh Corn: Using canned or defrosted frozen corn is the easiest approach for this salad (and makes it doable year-round!), but if fresh corn is in season, feel free to use that instead. Trim off the silk and leaves at the top of the ear of corn and pull off any loose pieces of husk. Then put the corn (still in its husk) on a plate in the microwave and microwave for around 4 minutes, depending on how large your ear of corn is. (If you are using 2 ears, add another 2-3 minutes to cook time.) Remove plate from microwave, and let corn rest for 5 minutes to cool down. When corn is cool enough to handle, peel back husk and remove corn silk. Stand ear of corn upright (upside-down) in large bowl, holding it by the husk. Then slice down with a chef's knife to remove the kernels.