Rinse the quinoa under cold water and place in a small saucepan with the water.
Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes until the water is absorbed.
Pat the salmon fillet completely dry with a paper towel and season both sides with sea salt and black pepper.
Heat the olive oil in a stainless steel or cast iron skillet over medium-high heat until shimmering.
Place the salmon in the pan and sear for 4 minutes without moving it to develop a golden crust.
Flip the salmon and cook for another 3 minutes, then remove from the pan to rest.
Mince the garlic and finely chop the fresh dill.
Fold the garlic, dill, lemon juice, and baby spinach into the hot quinoa until the greens are lightly wilted.
Plate the lemon-dill quinoa and top with the seared salmon fillet.