Rinse quinoa under cold water in a fine-mesh sieve until water runs clear.
Combine quinoa, water, and 1/2 teaspoon sea salt in a medium saucepan and bring to a boil.
Reduce heat to low, cover, and simmer for 15 minutes or until liquid is fully absorbed.
Remove from heat and let stand covered for 5 minutes; fluff with a fork and spread on a tray to cool completely.
In a large bowl, combine the cooled quinoa, parsley, mint, tomatoes, cucumber, and green onions.
In a separate small bowl, whisk olive oil, lemon juice, kosher salt, and black pepper until emulsified.
Pour dressing over the quinoa mixture and toss thoroughly to ensure even distribution.
Refrigerate for at least 30 minutes to allow the quinoa to absorb the dressing flavors before serving.