1) Prep: Wash 6–8 medium lemons. Using a fine zester or microplane, remove the yellow zest from 4 of the lemons (avoid the bitter white pith). Juice all the lemons until you have about 1 to 1 1/4 cups (240–300 mL) of fresh lemon juice. 2) Make syrup: In a saucepan combine 1 cup (200 g) granulated sugar and 1 cup (240 mL) water. Warm gently over medium heat, stirring until the sugar fully dissolves. Do not boil aggressively. 3) Infuse zest: Add the lemon zest to the hot syrup, reduce heat to low, and simmer gently for 2–3 minutes to release the oils. Turn off the heat and let the zest steep in the syrup for 20–30 minutes (longer for more intense flavor, up to 1 hour). 4) Strain: Strain the syrup through a fine-mesh sieve or cheesecloth into a clean bowl to remove all zest and any solids. Press or squeeze to extract as much liquid and oil as possible. Discard solids. 5) Finish cordial: While the syrup is still warm (but not hot), stir in the fresh lemon juice. If using, add 1/4 to 1/2 teaspoon citric acid (optional) to stabilize brightness and extend shelf life. Taste and adjust: if too tart, add up to 1–2 tablespoons simple syrup or a pinch of sugar; if too sweet, add a little more lemon juice. 6) Cool and bottle: Allow the cordial to cool to room temperature. Transfer to a sterilized glass bottle or jar, seal tightly, and refrigerate. 7) Use: Typical dilution for drinks is 1:3 to 1:6 (cordial:water or soda) depending on desired sweetness and intensity; for cocktails use 15–30 mL (1/2–1 fl oz) per drink per taste. Shake well before each use. 8) Discard: If the cordial becomes cloudy, develops off smells, visible mold, or any fermentation (bubbling), discard immediately.