Wash limes under running water and roll them on the counter to soften for easier juicing.

Cut limes in half and juice using a citrus juicer or reamer to yield 1 cup of juice.

Strain the lime juice through a fine mesh strainer or cheesecloth into a clean bowl to remove pulp and seeds.

Combine 1/2 cup water and 1 1/2 cups sugar in a medium saucepan and heat over medium heat, stirring for 3 to 5 minutes until the sugar fully dissolves.

Remove the saucepan from heat and stir in the strained lime juice, then let the mixture cool for 2 to 3 minutes.

Stir in the lime zest, citric acid, and a pinch of salt.

Pour the cordial into a clean glass jar or bottle and let it cool to room temperature.

Refrigerate for at least 2 hours before using; mix 1 part cordial with 3 to 4 parts water to serve.