Preheat the oven to 400°F and line a baking sheet with parchment paper or aluminum foil.
Place the salmon fillets on the baking sheet, and drizzle with 1 tablespoon olive oil, salt, pepper, and garlic powder.
Bake the salmon for 15-18 minutes, or until the salmon flakes with a fork and looks cooked through -- not overcooked! Allow salmon to cool.
Meanwhile, combine ½ cup raw quinoa with ¾ cup water in a medium-small pot. Bring water to a boil, then cover and reduce to a simmer, cooking for 20 minutes. Once cooked, allow to cool with the lid on for 5 minutes, then remove the lid and fluff the quinoa with a fork. Allow to cool completely in the pot.
While quinoa is cooking, make homemade croutons by placing the cubed bread onto a baking sheet and drizzling with 1 tablespoon olive oil and a pinch of salt and pepper. Bake for 15-18 minutes. Allow to cool.
Next, prepare the dressing by whisking together everything in a medium bowl or container. Add more olive oil or water, as needed, to thin out the dressing.
To assemble the salad, arrange lettuce, cooked quinoa, cherry tomatoes, avocado, and homemade croutons onto a large plate or bowl. Add enough dressing to the salad to coat, and mix. Carefully add the flaked salmon to the top of the salad. Drizzle with remaining dressing if necessary, as garnish!