Prepare the cucumber: Grate the cucumber using a box grater or the coarse side of a cheese grater. You should end up with about 200g of grated cucumber. Place it in a clean kitchen towel or double layer of muslin cloth, and squeeze firmly over the sink to extract as much liquid as possible. The cucumber will feel dry and compact in your hand—this is exactly what we want. You should get about 100ml of liquid from a good squeeze.

Strain the yoghurt: Line a fine-mesh sieve with a coffee filter, a clean muslin cloth, or a double layer of kitchen paper. Place the sieve over a bowl, spoon the Greek yoghurt into it, and let it drain in the refrigerator for at least 30 minutes. After this time, you will notice a pool of clear liquid (the whey) in the bowl, and the yoghurt will have thickened to a near-cream-cheese consistency.

Combine the base: In a medium mixing bowl, combine the strained yoghurt, the squeezed cucumber, and the minced garlic. Stir with a wooden spoon or spatula until everything is evenly distributed. The mixture will look thick and slightly lumpy from the cucumber, but that is perfectly fine.

Add the seasonings: Pour in the olive oil, lemon juice, white wine vinegar, salt, pepper, and the pinch of sugar if using. Stir gently but thoroughly until the oil is emulsified and the mixture takes on a pale, creamy green colour from the herbs. The aroma at this point will be sharp, fresh, and slightly garlicky.

Fold in the herbs: Add the chopped dill and mint. Gently fold them into the tzatziki until they are evenly distributed. You should see vibrant flecks of green throughout the creamy white base. Taste a small spoonful—the flavour should be bright, tangy, and balanced, with the garlic providing a gentle warmth on the back of the tongue.

Chill and rest: Transfer the tzatziki to a clean bowl, cover it tightly with cling film, and refrigerate for at least 1 hour. This resting time is crucial; it allows the flavours to meld and the garlic to mellow slightly. The texture will also firm up further as it chills. When you remove it from the fridge, the surface should look smooth and glossy.

Final taste and adjust: Just before serving, give the tzatziki a final stir and taste again. You may want to add an extra squeeze of lemon for brightness or a pinch more salt to bring the flavours together. Give it one last stir to incorporate any adjustments.

Plate with finesse: Spoon the tzatziki into a wide, shallow serving bowl. Use the back of your spoon to create a gentle swirl on the surface. Drizzle a generous swirl of extra-virgin olive oil over the top, and garnish with a few extra dill sprigs, a mint leaf, and a light sprinkle of flaky sea salt or black sesame seeds. This final touch is what elevates the dish from simple to stunning.