Grate the cucumber using the large holes of a box grater.
Place the grated cucumber in a fine-mesh sieve or cheesecloth and squeeze out as much liquid as possible.
Add the drained cucumber to a large mixing bowl.
Stir in the Greek yogurt, fresh dill, garlic, olive oil, lemon juice, and salt.
Mix until everything is smooth and well combined.
Let the Tzatziki Sauce Recipe rest for 10–15 minutes so the flavors blend together.
Taste and adjust the seasoning with extra lemon juice, dill, or salt if desired.
Serve immediately or chill before serving.