Ingredients: grapefruit, lemon, soda water, sugar.

The skin of grapefruit is scrubbed clean with salt water, the skin is shaved (not to the white part), and the pulp is picked out.

Two bowls of water in a pot, heat and melt eight rock candy, add grapefruit peel and cook for 10-15 minutes.

Pour in the grapefruit flesh, squeeze the juice of half a lemon into it and simmer over a low heat, stirring, until the sauce thickens.

Serve the grapefruit sauce, let it cool, then add some honey and mix well.

The sauce is sweet and sour, and can be stored in the refrigerator for use as a drink or tea.

Boil the grapefruit sauce, tea bags (or wrapped tea leaves), and lemon slices in water. Add a little hot water to the grapefruit sauce, add soda water to more than half the height of the glass, add a thick layer of ice cubes, and top with the grapefruit slices. The ice cubes will top the grapefruit slices at the very top, which is very special. (Do the same with oranges.)