Cover the 2 cups of dry quinoa with 4 cups of water in a medium saucepan, over high heat on the stove. Bring to a boil, then reduce the temperature and cover for 15 minutes, until the quinoa has absorbed all of the water. Fluff with a fork, and allow to cool while you chop the vegetables and herbs. (Alternatively, you can cook the quinoa in the Instant Pot)
In the meantime, mix together the lemon juice, olive oil, 1 teaspoon of sea salt and fresh black pepper in a large bowl. Add the cooked quinoa, and toss in the dressing to coat well.
Add in the scallions, dill, parsley, cucumber, red pepper, and olives, if using, and toss well to combine. Season with additional salt and pepper, if desired. (I sometimes add up to 1 teaspoon more salt, to taste.)
Allow the mixture to marinate at least an hour before serving, or chill in the fridge overnight. This salad can be served cold or at room temperature, and should keep in an airtight container in the fridge for up to 5 days.