Wash the lemons hot, grate them dry, finely grate the peel and squeeze the juice. Bring 300 ml water with sugar, lemon grated and juice to the boil and simmer for about 10 minutes. Remove from the heat and let it cool down slightly.
Half fill glasses (approx. 300 ml content) with ice cubes and add 1 tablespoon of syrup each. Add approx. 75 ml coffee and fill up with tonic water. The refreshing coffee lemonade is ready.