In a medium saucepan, combine the rinsed quinoa and vegetable broth (or water). Bring to a boil over high heat.
Once boiling, reduce the heat to low, cover with a lid, and let simmer for about 15 minutes, or until the liquid is absorbed and the quinoa is tender. Fluff with a fork and set aside to cool slightly.
While the quinoa is cooking, prepare the veggies. In a large mixing bowl, combine the cherry tomatoes, cucumber, bell pepper, Kalamata olives, and red onion.
In a small bowl, whisk together the olive oil, lemon juice, oregano, salt, and pepper. Pour this dressing over the mixed vegetables and toss well to combine.
Once the quinoa has cooled slightly, add it to the bowl with the dressed vegetables and mix thoroughly.
To serve, spoon the quinoa and vegetable mixture into individual bowls. Top each bowl with sliced avocado and crumbled feta cheese.
Finish with a sprinkle of fresh parsley for garnish.
Notes
Feel free to customize the vegetables based on your preference.