Grate the cucumber using a box grater and place it in a towel.
Gently squeeze the cucumber to remove excess water.
Set the cucumber aside.
In a mixing bowl, combine the Greek yogurt, garlic, lemon juice, olive oil, dill, and mint.
Mix until well combined.
Add the grated cucumber and stir until evenly distributed.
Season with salt and pepper to taste.
Mix thoroughly and adjust the seasoning if necessary.
Cover the bowl with plastic wrap and refrigerate for at least 1 hour to let the flavors meld.
When ready to serve, give the tzatziki a good stir.
Enjoy it as a dip, spread, or sauce.