Put the sugar and 1.5 litres/2¾ pints water into the largest saucepan you have.
Gently heat, without boiling, until the sugar has dissolved.
Give it a stir every now and again. Pare the zest from the lemons using a potato peeler, then slice the lemons into rounds.
Once the sugar has dissolved, bring the pan of syrup to the boil, then turn off the heat.
Fill a washing up bowl with cold water. Give the flowers a gentle swish around to loosen any dirt or bugs.
Lift flowers out, gently shake and transfer to the syrup along with the lemons, zest and citric acid, then stir well.
Cover the pan and leave to infuse for 24 hrs.
Line a colander with a clean tea towel, then sit it over a large bowl or pan. Ladle in the syrup – let it drip slowly through.
Discard the bits left in the towel.
Use a funnel and a ladle to fill sterilised bottles (run glass bottles through the dishwasher, or wash well with soapy water. Rinse, then leave to dry in a low oven).
The cordial is ready to drink straight away and will keep in the fridge for up to 6 weeks. Or freeze it in plastic containers or ice cube trays and defrost as needed.
