1.Combine dye, one cup of the measured warm water and the vinegar in a glass jug or bowl and stir to dissolve the dye. Add the dye mixture to a large saucepan with the remaining water.
2.Wash the eggs well and add them to the saucepan in a single layer (or cook in two batches if necessary – if eggs are crowded in the pan they will not colour evenly). Bring water to the boil. Simmer, uncovered, for 15 minutes, then gently remove the eggs and allow to cool.
3.Polish the eggs with a lightly oiled cloth before using.
The dye is strong and will stain – use old utensils and disposable gloves. It is available from greek, and some supermarket, delicatessens. You can substitute a strong gel or powdered food colour if preferred. Liquid food colours will not give an intense colour. Can be made up to three days ahead. Not suitable to freeze. Not suitable to microwave.