Wash and dry the cucumber then finely grate it using a box grater or food processor fitted with the grating blade.
Place the grated cucumber into a fine-mesh strainer and sprinkle with ½ teaspoon salt. Allow it to sit for 10 minutes.
After 10 minutes, place the cucumber into a piece of cheesecloth and squeeze out any excess liquid. Alternatively, you place the cucumber in a mesh strainer and use a cup or spoon to press the excess liquid out of the cucumber.
Mix together the yogurt, garlic, remaining salt, olive oil, lemon juice, and dill together until well combined. Gently stir in cucumber.
Refrigerate for at least 60 minutes before serving.
When ready to serve, drizzle with olive oil if desired.
Storage: Tzatziki Sauce is best served within 48 hours of preparation, but can be stored in an airtight container for up to 3 days in the refrigerator. Using a Garden Cucumber: If using garden cucumber in place of an English Cucumber, be sure to peel and seed before grating. Yogurt: Non-fat, whole milk, or 2% plain Greek yogurt are all suitable for Tzatziki. For an authentic, luscious sauce, I advise using whole milk yogurt. Dill: Omit the dill if serving with curries. If you don't have fresh dill, use ½ teaspoon dried dill weed.