Preheat your oven to 400°F and line a baking sheet with parchment paper.
Rinse the quinoa under cold water, then combine with 1/2 cup water in a small pot; bring to a boil, reduce to low, cover, and simmer for 15 minutes.
Toss the asparagus with half of the olive oil and a pinch of salt, then roast in the oven for 10-12 minutes until tender.
In a small bowl, whisk together the Greek yogurt, lemon juice, and fresh dill if desired to create the sauce.
Heat the remaining olive oil in a non-stick skillet over medium-high heat.
Season the salmon with salt and pepper, then sear for 4-5 minutes per side until the skin is crisp and the fish is cooked through.
Toast the walnuts in a dry pan over medium heat for 2 minutes until fragrant.
Fluff the quinoa with a fork and plate it alongside the roasted asparagus.
Top the quinoa with the seared salmon, a dollop of the lemon-yogurt sauce, and a sprinkle of toasted walnuts.