Add the 6 black tea bags to the 1.65 litres of cold filtered water in a large pitcher or jar. Cover tightly and refrigerate for 8–12 hours. Eight hours produces a lighter, more delicate result; twelve hours produces a fuller-bodied brew with more depth — both work well depending on personal preference. Remove the tea bags after brewing without squeezing. Squeezing releases bitter tannins into an otherwise smooth, clean base and is the most common way to ruin a cold brew. The finished tea should taste naturally sweet, smooth, and clean with no bitterness or astringency whatsoever. If it tastes bitter, the bags were left in too long or squeezed — start again.

Rinse the rosemary sprig thoroughly under cold water and shake off excess moisture. Hold the sprig between both palms and clap firmly once or twice until you can clearly smell the essential oils releasing. This gentle activation is all the preparation rosemary needs for a cold infusion. Do not chop the sprig, strip the leaves, or bruise it aggressively — rough handling ruptures the cellular structure and releases harsh, resinous compounds that make rosemary taste medicinal and overpowering even in a brief infusion.

Add the prepared rosemary sprig directly to the cold brew tea base. Refrigerate and allow the infusion to develop for 6–8 minutes, tasting at the 6-minute mark. You're looking for a clear, clean piney-herbal aroma that is assertive but not aggressive — present in every sip without dominating everything else in the glass. Remove the rosemary sprig promptly the moment that balance is reached. In a cold infusion, rosemary develops more slowly than in warm liquid, but it still crosses from botanical to medicinal if left in too long. Do not rely on timing alone — always taste.

Add the two strips of lemon peel — yellow part only, with absolutely no white pith attached — to the cold brew and allow them to infuse for 5 minutes, then remove. This step is purely aromatic: lemon peel releases fragrant citrus oils into the liquid that add brightness and elegance without contributing any acidity. Pith introduces a sharp, unpleasant bitterness that is very difficult to correct after the fact, so take care when peeling — a sharp vegetable peeler rather than a knife gives the most consistent results.

Stir in 2 tablespoons of mild honey. Cold liquid does not dissolve honey as readily as warm liquid, so stir patiently and thoroughly until no streaks remain at the bottom of the pitcher. Taste and add up to 1 additional tablespoon only if the base still tastes noticeably bitter or sharp. The finished drink should lean dry — honey is present as a rounding tool to smooth the black tea's natural tannins and bridge the rosemary and lemon elements, not to make the drink taste sweet. If it tastes obviously sweet, too much honey was added.

Stir in 1 tablespoon of fresh lemon juice. Taste carefully — the acidity should be barely perceptible, just enough to sharpen the profile and add a clean brightness to the finish. Add up to 1 additional tablespoon only if the drink still feels flat or one-dimensional. Lemon juice in this recipe is a correction and a finishing tool, not a base flavour — use it with restraint. More than 2 tablespoons total will push the acidity too high and compete with the rosemary character.

Refrigerate the finished tea for a further 1–2 hours until completely cold and the flavours are fully integrated. Fill glasses generously with ice, pour the chilled tea over the ice, and garnish with a fresh rosemary sprig and a twist of lemon peel. Serve immediately while the aroma is at its most expressive.