In a saucepan, heat the water and sugar over medium heat until fully dissolved.

Add the ground coffee (or instant coffee) and stir well. Let it simmer gently for about 10-15 minutes, then remove from heat.

If using a vanilla bean, split it open and add it to the mixture. Let it steep while cooling.

Once the coffee mixture has cooled to room temperature, strain it through a fine-mesh sieve or cheesecloth to remove coffee grounds.

Stir in the vodka (or rum). If you opted for vanilla extract instead of a bean, add it now.