Rinse quinoa under cold water using a fine mesh sieve.
In a medium saucepan, combine quinoa and water and bring to a boil.
Reduce heat to low, cover, and simmer for about 15 minutes, or until water is absorbed and quinoa is tender.
Remove from heat and fluff quinoa with a fork; let cool slightly.
While quinoa cooks, massage torn kale with a pinch of salt for 2-3 minutes until it softens and darkens.
In a small bowl, whisk together olive oil, lemon juice, Dijon mustard, sea salt, and black pepper until smooth.
In a large bowl, combine cooled quinoa, massaged kale, diced avocado, chopped cucumber, red bell pepper, and red onion.
Pour the lemon Dijon vinaigrette over the salad and toss gently to combine.
Sprinkle crumbled feta cheese on top and serve immediately or chill for 15 minutes to meld flavors.