Preheat oven to 400°. Line a baking sheet with foil and place salmon filet on foil. Sprinkle with 1/2 tsp. salt and ground pepper, to taste.
Bake salmon until it's no longer opaque in the center, roughly 15-20 minutes. Remove salmon from oven, separate from skin and break into pieces.
While salmon is cooking, bring 1-inch of water to a boil in a saucepan with steamer. Add green beans and cover, cooking until tender, about 5 minutes. Immediately rinse beans under cold water, drain.
Rinse saucepan, then combine 1-3/4 cup water, 3/4 cup quinoa, and 1/8 tsp salt in the saucepan. Bring to a boil, then reduce heat to low, covering. Simmer until quinoa is tender, about 15 minutes. Fluff quinoa with a fork.