1. Using a peeler thinly peel just the rind of 2 lemons. Place in a bowl with the juice or all 4 lemons, tartaric acid and sugar.
Step 2
2. Pour over boiling water and leave to stand until cool. Strain and bottle and keep refrigerated until required. Make up using 1 part syrup to 3 parts water or try with Lemonade or soda water.