Bring a large pot of water to a boil. Rinse the quinoa in a fine mesh strainer for around 30 seconds, then add to the boiling water and cook uncovered for 10-12 minutes then drain.
Return drained quinoa to the pot and cover. Allow it to sit off heat for 5-10 minute to steam and finish cooking. Then uncover and allow to cool. If making the quinoa ahead refrigerate until ready to use.
Add the spring mix and quinoa in a large mixing bowl and toss until well combined. Alternatively, you can add the spring mix to individual bowls and top with a portion of the quinoa.
Add the tomato, cucumber, green pepper, and onion then top with feta cheese and olives and serve with the red wine vinaigrette.
Red Wine Vinaigrette
Add all ingredients to a bowl and whisk to combine until emulsified. If possible allow the dressing to sit for around 30 minutes for flavors to combine and whisk again just before serving.