Put a pot on stove and pour in the wine and water, add sugar, vanilla essence, cloves, cinnamon stick and orange slice and slowly bring to a boil.
When the wine comes to a boil, bring the temperature down to a light simmer and let it cook for a couple of minutes, stirring occasionally to melt the sugar. The wine should never boil vigorously, but gently. The longer you boil the wine, the less alcohol it will contain.
Serve hot in glasses or cups, decorated with orange slices.