Rinse quinoa thoroughly in a fine-mesh sieve. In a medium saucepan, combine quinoa, 2 cups of water or broth, and 1/4 tsp salt. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes until liquid is absorbed. Remove from heat, let stand covered for 5 minutes, then fluff with a fork.

While quinoa cooks, prepare the vegetables and dressing. Chop the cucumber, halve tomatoes and olives, and slice the onion. In a jar with a lid, combine all vinaigrette ingredients and shake vigorously until emulsified.

Pat salmon fillets completely dry with paper towels. Season all sides with 1/2 tsp kosher salt, 1/4 tsp black pepper, and 1/2 tsp dried oregano.

Heat 1 tbsp of olive oil in a large non-stick skillet over medium-high heat until shimmering. Place salmon skin-side down and press gently with a spatula for 15 seconds. Cook for 4-6 minutes until the skin is crispy and releases easily.

Flip the salmon and cook for another 2-4 minutes for medium-rare (130-135°F). Remove from the pan and let it rest for a few minutes.

To assemble, divide the quinoa among four bowls. Top with cucumber, tomatoes, olives, and red onion. Place a salmon fillet in each bowl. Drizzle generously with the vinaigrette and serve.