Squeeze the juice from the grapefruit and lime, stir.
Put ice in a glass, add sugar syrup. Homemade sugar syrup recipe:
Cane sugar - 300 gr; Water - 300 ml. Mix the water and sugar in a saucepan and start to heat gradually, stirring occasionally. The sugar should dissolve completely. When the water starts to boil, remove from heat and cool. Store the finished syrup in a tightly closed glass bottle or jar for up to 2 weeks.
Pour the grapefruit-lime juice through a sieve, add mineral water. Stir.
Then add beer to the rim of the glass and decorate with a lime slice.
Enjoy!