Tzatziki sauce

Why tzatziki sauce goes watery, and how to stop it

Cucumber is about 95% water, and salt pulls that water out whether you want it to or not. If you stir raw grated cucumber straight into yogurt, the salt in the sauce draws the water out overnight and you open the container to a thin pool on top. Salting the cucumber first and wringing it out in a towel gets that water out before it can reach the yogurt. It is the one step that separates tzatziki that holds its shape on a gyro from tzatziki that runs off the plate.

Grate the cucumber rather than dicing it. Grated cucumber spreads through the sauce and gives up its water easily. Diced cucumber keeps its water and releases it slowly into the sauce over the next day.

Which yogurt to use

Whole-milk Greek yogurt, and it makes a bigger difference than any other ingredient. The fat carries the garlic and rounds off the tang, and strained yogurt is thick enough to take the oil and lemon without loosening. Nonfat Greek yogurt works but tastes sharper and a little chalky; add another tablespoon of olive oil to make up for it. If all you have is regular plain yogurt, start with about 4 cups and strain it in a strainer lined with cheesecloth or a coffee filter, in the fridge, for 2 to 3 hours, until you have about 2 cups.

Dairy-free tzatziki sauce

For a dairy-free or vegan tzatziki, swap the Greek yogurt for 2 cups of a thick, plain, unsweetened plant yogurt. Read the label: many plant yogurts sold as "plain" still have added sugar, and vanilla or sweetened ones will not work at all.

• Greek-style almond or cashew yogurt is the best match. It is thick and mild, and the garlic and lemon cover what little nut flavor it has.
• Soy yogurt is usually thinner, but it has the most protein of the plant yogurts.
• Coconut yogurt is thick and creamy, but it tastes of coconut, and most of its fat is saturated. It works if you do not mind the flavor.

Three things change. Plant yogurts are less tangy, so add another 1 to 2 tsp of lemon juice. Most are thickened with starch or pectin rather than strained, so straining them does little; buy the thickest one you can, and squeeze the cucumber especially well, since a looser yogurt shows any extra water. And the protein mostly goes: dairy Greek yogurt gives this sauce its 6 g of protein a serving, while plain almond, cashew and coconut yogurts have much less, though some Greek-style ones add pea or soy protein. Check the label if that matters to you. Dairy-free tzatziki keeps about 3 days in the fridge.

Garlic: less than you think, and let it sit

Raw garlic keeps getting stronger for hours after it is mixed in, so tzatziki that tastes balanced at the counter can be fierce the next morning. Two cloves for two cups of yogurt is a moderate amount. Letting the grated garlic sit in the lemon juice first softens its bite. The thirty-minute chill matters for the same reason: it gives the garlic time to spread evenly instead of landing in hot spots.

Dill or mint

Dill is the usual choice in American Greek restaurants. Many cooks in mainland Greece leave herbs out entirely, and mint is the norm in the Turkish and Cypriot versions of the sauce. All of them are right. If you only have dried herbs, use about 1 teaspoon of dried dill or dried mint.

What to eat it with

• Grilled or broiled meat: souvlaki, lamb chops, chicken thighs, or gyros in pita.
• Falafel, instead of or next to tahini sauce.
• Raw vegetables as a dip. It is far lighter than a sour-cream ranch dip.
• Roasted potatoes or baked salmon, where it works as a cold sauce against something hot.
• A Greek salad and bread, for a whole meze table.

Keeping it

Four days in a covered container in the fridge. A little liquid may still collect on top; stir it back in rather than pouring it off, since that is flavor. Tzatziki does not freeze well: the yogurt turns grainy and the cucumber goes limp when it thaws.

What it is worth nutritionally

A serving (about 1/3 cup) is about 100 kcal with 6 g of protein. Most creamy dips get nearly all their calories from fat. Strained yogurt adds real protein, so tzatziki gives you 6 g a serving alongside the fat. About half of that fat is the olive oil, so you can cut it back if calories matter to you, and the sauce will still hold together.