Bring water to a boil and add couscous, olive oil, and salt. Simmer until tender and water is absorbed. Turn off heat, cover the pan, and let it steam for a few minutes so the grains stay fluffy.
Preheat the oven to 350°F (175°C). Drizzle salmon with olive oil and rub in paprika, oregano, salt, and pepper. Bake for 13–16 minutes, until flaky. Squeeze fresh lemon juice over the warm salmon before serving.
Whisk together Greek yogurt, mayo, sour cream, lemon juice, dill, salt, and pepper. Mix until smooth and creamy. Taste and adjust seasoning if needed.
Add a scoop of couscous to each bowl. Top with arugula, tomatoes, cucumbers, and red onion. Place a piece of salmon on top and drizzle generously with the creamy dill sauce. Finish with optional olive oil, vinegar, or extra lemon.