Rinse quinoa under cold water.
In a pot, bring water and salt to a boil.
Add quinoa, reduce heat, cover, and simmer for 15 minutes.
Remove from heat, let it sit for 5 minutes, then fluff with a fork.
In a large bowl, combine quinoa, tomatoes, cucumber, red onion, parsley, and feta.
Drizzle with olive oil and lemon juice.
Season with salt and pepper, toss to combine.