To make tamarind paste, combine ½ cup of fresh, sweet tamarind fruit or pre-packaged wet tamarind block with 1 cup of hot water. Mash with your fingers until the fruit dissolves into the water. Strain the fibers and seeds out with your fingers or a fine mesh strainer. The resulting paste should be about the consistency of ketchup.
Heat ½ cup of the tamarind paste, 2 cups water, and ¼ cup sugar over medium heat until the sugar dissolves. The sweetness of the drink will depend on your tamarind. If it's too sweet, add a little more tamarind paste or some lime juice. If it's too sour, add more sugar.
Cool the tamarind drink in the fridge. Fill a glass with ice and then pour the tamarind drink over. Garnish with a slice of lime and a sprig of mint.