Preheat the grill to medium-high heat.
In a medium saucepan, bring vegetable broth (or water) to a boil, add quinoa, cover, and simmer for 15 minutes until fluffy.
While the quinoa cooks, season the salmon fillets with olive oil, salt, pepper, and dried oregano.
Grill salmon for about 5-6 minutes per side or until cooked through and flaky.
In a large bowl, combine cooked quinoa, spinach, cherry tomatoes, cucumber, red onion, and feta cheese.
Drizzle with olive oil and lemon juice, tossing gently to combine.
Serve the grilled salmon atop a generous scoop of the quinoa salad with lemon wedges on the side.