Halakhah zu Bereschit 28:12

Sour "Lemons" are forbidden by some when they are squeezed into an empty bowl, even if they will later be used for food, since in lands where many lemons grow, they are used to squeezing them for their juice, in order to prepare the drink known as 'Limonada', and they fill up barrels of juice for this purpose. Even though the blessed Shulchan Aruch allowed the squeezing of lemons, those who forbid it nowadays make sense, and therefore modern authorities forbid squeezing it into an empty vessel. However, one who wishes to prepare 'Limonada', which is a beverage made of squeezed lemons together with sugar and water, they should first put the sugar in a bowl and squeeze lemons over it, and only then pour over water. But do not put the water before the squeezing of the lemons. They have found a sign for this in the Torah (Genesis 28:12) "Behold, a ladder (sulam) standing on the earth". The word Sulam is the initials of the words Sugar, Lemon, Mayim (water), which is the order that the lemonade is to be made.