Squeeze the lemons and grate the zest of one lemon.
Boil the water with sugar, lemon juice and lemon zest in a saucepan and simmer for about 5 minutes. Set the liquid aside and let it cool.
After the lemon mixture has cooled down, briefly froth the chickpea water with the mixer, add baking powder and 0.5 ml lemon juice and whip for 4 minutes until it is firm.
If you like, you can sieve the zest from the lemon-sugar-water. Now simply mix the liquid with aquafaba (chickpea water mixture) and freeze the mass or put it in the ice cream machine. The mixture does not have to be perfectly mixed, this is done later while stirring in the ice cream machine or by hand.