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Place a clean tea towel or cheesecloth in a fine mesh strainer. Set the strainer over a bowl and spoon 1 cup (245 g) of plain, unsweetened yogurt directly into the towel. Place the bowl with the strainer in the fridge for about 2 hours. As it sits, the liquid from the yogurt will drip into the bowl. Discard this liquid and use the strained yogurt in the towel for your sauce. Wash a medium-sized cucumber and cut it in half. Peel the cucumber and slice it in half lengthwise. Use a spoon to scoop out and discard the seeds. Take a sharp knife and carefully dice the cucumber into small pieces. You can save the other half of the cucumber to use in another recipe. Lay a clean tea towel on the counter and scoop the diced cucumber into the center of it. Gather up the ends of the towel so the cucumber is wrapped tightly in the towel. Squeeze the cucumber in the towel over a sink so any excess liquid comes out of the cucumber. Open the towel and spoon the cucumbers into a medium bowl. Add the strained yogurt along with the rest of the sauce ingredients. Stir the sauce until it's combined. You can store leftover sauce in an airtight container for up to one week. You'll need to stir in:  1 pinch kosher salt. 2 cloves minced garlic. 1/2 tablespoon (7 ml) olive oil. 1 teaspoon (5 ml) red wine vinegar. 2 to 3 fresh minced mint leaves.

Summary:
Strain the yogurt. Wash and cut the cucumber. Squeeze and strain the cucumber. Combine the tzatziki sauce.