Step 1

Cut thin slices of lemon peel from the whole of each lemon using a vegetable peeler or small sharp knife. You only need the yellow part, not any white pith as this will make the lemonade bitter.

Step 2

Place the lemon peel in a small non-reactive saucepan. This is a saucepan that's made from a material that won't react with the acidic lemon juice. A non-stick saucepan would be ideal, and avoid pans that are made from aluminium, unlined copper or tin.

Step 3

Pour in 200ml cold water to cover the lemon peel and place on a low heat. Gently simmer for 10 minutes to infuse the water with the flavour and colour of the lemon peel.

Step 4

Remove from the heat and strain into a heatproof jug, discarding the lemon peel. Stir in the sweetener and stir until dissolved. Leave the lemon syrup to cool.

Step 5

Squeeze the juice from the lemons and strain into the jug using a nylon sieve (metal sieves may react with the lemon juice).

Step 6

Make up to 1 litre with cold water and stir. Chill if wished, and serve in glasses with ice, lemon slices and mint sprigs (optional).