Place the quinoa in a fine strainer and rinse well under cold water. Transfer it to a small saucepan with 2 cups of water. Bring to a boil over medium heat. Once boiling, lower the heat to a gentle simmer, cover, and cook for about 15 minutes or until the water is absorbed. Remove from heat, fluff with a fork, and allow it to cool for 5 to 10 minutes.
In a large mixing bowl, combine the cooled quinoa with cucumber, parsley, mint, red onion, pistachios, and chickpeas.
Pour in the fresh lemon juice and olive oil. Season with sea salt and black pepper. Add the crumbled feta cheese and gently mix until everything is evenly combined.
Serve right away, or cover and refrigerate for a few hours to let the flavors blend together before serving.
Store leftovers in an airtight container in the refrigerator for up to 5 days.