Bring a large pot of salted water to a boil and add your pasta. Cook it until al dente, following the package instructions closely. Drain it and rinse briefly under cool water to stop the cooking and prevent sticking.
Place your salmon fillets on a lined baking sheet and drizzle with olive oil, salt, and pepper. Roast at 400°F for about 12 to 15 minutes, until the fish flakes easily with a fork. Let it cool slightly before flaking it into bite-sized pieces.
In a mixing bowl, combine the Greek yogurt, grated cucumber, garlic, dill, and lemon juice. Stir everything together until smooth and creamy. Taste and adjust the salt or lemon to your liking before setting it aside.
Add the cooled pasta to a large bowl along with the flaked salmon, cherry tomatoes, red onion, and feta. Pour the tzatziki sauce over the top and gently fold everything together. Try not to overmix so the salmon stays in nice, tender pieces.
Cover the bowl and refrigerate for at least 20 minutes before serving. This resting time lets the flavors settle in and blend together nicely. A short chill also makes the salad taste even more refreshing on a warm day.