Chop the ginger and grate it roughly in a mortar. Stir in a saucepan with 1 to 1.5 liters of water, bring the ginger stock to a boil and simmer for a few minutes.
If you don`t want the ginger pieces in the lemonade, you should let the brew cool down for a few minutes and then pour it through a sieve lined with a kitchen towel. Collect the liquid.
In another small saucepan at low temperature, dissolve the sugar in 500 ml of water and then add this to the ginger stock.
In the meantime, squeeze the limes and chop the basil. Add the lime juice and basil to the sweet ginger stock. Let it cool completely.
If you like it a little more tangy, only take 1 l of water at the beginning and then fill up the lemonade with 0.5 l of mineral water at the end.