In a large bowl, combine the plain whole milk yogurt and the fine sea salt. Stir thoroughly until the salt is completely dissolved and evenly distributed throughout the yogurt. The salt performs two functions here: it seasons the labneh throughout rather than only on the surface, and it draws moisture out of the yogurt during the straining process through osmosis — salted yogurt drains more efficiently and more completely than unsalted, producing a firmer, better-seasoned result in the same straining time. Do not skimp on the mixing — uneven salt distribution produces labneh that is salty in some bites and bland in others. Taste the salted yogurt mixture before straining: it should taste mildly but clearly seasoned. Whole milk yogurt is specified for two reasons that directly affect the quality of the finished labneh. First, its higher fat content produces a richer, creamier, more luxurious finished texture than low-fat or fat-free yogurt, which drain to a grainy, slightly dry result. Second, the milk fat carries the yogurt's aromatic compounds — the lactic acid bacteria's fermentation byproducts — that give labneh its characteristic tangy, complex, slightly funky depth. Skim or low-fat yogurt produces labneh with flat, one-dimensional flavour regardless of straining time.

Line a colander or fine-mesh sieve with two layers of clean cheesecloth. If cheesecloth is unavailable, a clean, thin cotton kitchen towel or a large coffee filter works as an effective substitute — any fabric or material that allows liquid to pass through while retaining the thickened yogurt solids. Place the lined colander over a deep bowl that will catch the draining liquid — the bowl must be deep enough to hold the collected whey without touching the bottom of the colander, as contact between the collected whey and the draining yogurt would slow and eventually stop the straining process. Pour the salted yogurt mixture into the cheesecloth-lined colander, distributing it evenly. For firmer labneh — the kind that can be shaped into balls or sliced — gather the four corners of the cheesecloth and tie them together above the yogurt to form a bundle, then suspend the bundle from a wooden spoon laid across the top of a deep pot, allowing the whey to drip freely from the bottom of the bundle. This hanging method increases the rate of draining by allowing gravity to act on the yogurt from all sides simultaneously rather than only from the bottom. For the standard spreadable version, simply leaving the yogurt in the cheesecloth-lined colander over the bowl is sufficient — the weight of the yogurt presses down on itself and drives the whey out gradually through the cloth.

Cover the colander or bundle with plastic wrap or a clean cloth to prevent the yogurt from absorbing refrigerator odours and from developing a dry skin on the exposed surface. Place in the refrigerator and allow to strain undisturbed. The straining time determines the final texture and concentration of the labneh. At 24 hours the labneh is thick, creamy, and spreadable — similar to a very thick Greek yogurt or a soft cream cheese, easily scooped with a spoon and spread on bread. This is the texture for serving as a dip, spreading on flatbread, and using as a sauce base. At 48 hours the labneh has lost considerably more moisture and is noticeably firmer — closer to a fresh chèvre or cream cheese in density, holding its shape when scooped. This is the texture for rolling into balls, for using as a spread on bagels, and for placing under grilled meats where it needs to support the weight of the protein without spreading immediately. Do not drain beyond 48–60 hours as the labneh becomes very firm and increasingly acidic as additional whey is removed. The whey that drains into the bowl is clear to pale yellow and slightly tart — it can be retained and used in bread doughs, soups, and smoothies as a source of protein and lactic acid, or simply discarded.

Unwrap the cheesecloth and invert the labneh into a wide, shallow serving bowl. Use the back of a spoon to create a shallow, swirling well in the centre — press the spoon into the labneh and sweep outward in a slow circular motion, building a low ridge around the outside and a depression in the centre. This well collects the olive oil and provides the visual presentation style of labneh as it is served throughout the Levant. Drizzle the 3 tablespoons of extra-virgin olive oil generously into the well and over the surface — the oil pools in the depression and creates the glossy, inviting finish that is the visual signature of labneh presented correctly. Scatter za'atar or sumac across the entire surface to your preferred quantity — the garnish should be clearly visible and generously applied rather than a dusting. Serve immediately with warm bread alongside for dipping and spreading.