Grate cucumber coarsely over a strainer and large bowl. Squeeze and press out as much water as you can.
In a bowl, combine grated cucumber with yogurt, garlic, dill, olive oil, lemon juice and zest, and salt.
Refrigerate for at least an hour to chill and allow the flavours to meld.
Notes
Grate cucumber using a box grater, or use a food processor.
To avoid a runny sauce, it's important to remove as much liquid as possible from the cucumber after it's grated. You can do this by grating over a sieve, then pressing the excess water out with a spoon. You can also wrap the grated cucumber in paper towels or cheesecloth, then gently squeeze over the sink until most of the excess moisture is removed.
Although English cucumbers are easy to use because you don't need to peel them, you can use garden cucumbers if that's what you have. Just be sure to peel them if the skin is tough.
You can enjoy your homemade tzatziki sauce right away, however, it does taste best after chilling in the fridge for at least an hour.
Store your delicious Greek yogurt sauce in an airtight container in the fridge for up to 4 days.