Preheat your oven to 400°F (or heat a grill or stovetop grill pan over medium-high heat).
- Rub the salmon fillets with olive oil and season with salt, pepper, dried oregano, and garlic powder.
- If baking, place the salmon fillets on a lined baking sheet and bake for 12-15 minutes, or until the salmon is cooked through and flakes easily with a fork. If grilling, cook the salmon fillets for about 3-4 minutes per side, depending on thickness, until the fish is cooked to your liking.
- While the salmon is cooking, prepare the salad. In a large bowl, combine the sliced cucumber, halved cherry tomatoes, red onion, Kalamata olives, feta cheese, and mixed greens.
- In a small bowl or jar, whisk together the olive oil, red wine vinegar, Dijon mustard, honey (if using), lemon juice, and dried oregano to make the dressing.
- Once the salmon is done, remove it from the oven or grill and let it rest for a couple of minutes. Then, break it into large pieces.
- Drizzle the dressing over the salad and toss gently to combine. Top the salad with the cooked salmon.
- Serve immediately, garnished with additional feta or olives if desired.