Vinaigrette: Whisk together all Vinaigrette ingredients.
Quinoa: Bring 1 cup water to a boil. Add quinoa and salt, then reduce heat to a simmer. Cook 10 to 15 minutes or until water is all absorbed. Fluff with a fork and set aside.
Eggs: Bring a medium saucepan of water (enough to cover eggs) to a boil. Carefully add eggs and cook for 6 minutes and 30 seconds. Drain water and add cold water to the pan to cool eggs. Dry and peel eggs.
Assemble: Toss spinach with balsamic vinaigrette. Add quinoa, avocado, feta, and red bell pepper and toss to combine. Top with halved soft-boiled eggs.