This tzatziki sauce recipe makes a thick, tangy Greek dip with Greek yogurt, cucumber, garlic, and dill, and a 15-minute salt-and-drain step keeps it spoonable instead of watery.
Wash and peel the cucumber completely, cut it in half lengthwise, and scoop out the seeds with a spoon.
Grate the cucumber halves on the large holes of a box grater (about 1 1/2 cups), set in a fine-mesh strainer over a bowl, sprinkle with 1/2 teaspoon salt, and rest 15 minutes.
Transfer the cucumber to a flour sack towel or double cheesecloth, twist into a bundle, and squeeze over the sink for about a minute until only a few drops fall (you should have about 3/4 cup), then fluff apart with a fork without rinsing.
Mince or grate the garlic into a paste, squeeze and measure 1 tablespoon lemon juice, and finely chop 1 tablespoon fresh dill.
Stir the Greek yogurt, garlic, olive oil, lemon juice, remaining 1/4 teaspoon salt, and black pepper with a silicone spatula for about 30 seconds until smooth and glossy.
Gently fold in the squeezed cucumber and chopped dill until evenly combined, then taste and adjust with a pinch of salt or a few drops of lemon juice if needed.
Cover and refrigerate at least 1 hour, stir before serving, and spoon into a shallow bowl to serve cold.
Notes
Squeeze the cucumber harder than seems reasonable; a quick squeeze leaves a puddle of liquid on top by the next morning.
Use full-fat strained Greek yogurt for the creamiest texture; nonfat versions make a looser, tarter sauce.
Grate on the large holes and seed the cucumber every time; the seed core is the wettest part.
English or Persian cucumbers have thin skin and few seeds, so they need less peeling and release less water.
Grate or mince the garlic very fine; large raw garlic pieces stay sharp even after chilling.
Garlic gets stronger over time, so lean toward less garlic if serving on day two or three.
Chop the dill right before mixing; if unavailable, use 1 teaspoon dried dill, though the flavor will be flatter.
Store in an airtight glass container in the refrigerator for up to 3 days; glass does not hold garlic odor like plastic.
Do not freeze; thawed tzatziki turns grainy and separates. Serve cold and never reheat.
Make ahead: squeeze the cucumber up to 1 day in advance, then mix the sauce the day you serve it.
If the sauce looks loose, stir in 1 to 2 tablespoons of fresh Greek yogurt to bring back the body.
Do not leave out more than 2 hours, or 1 hour if the room is above 90°F (32°C).