Boil 115g of sago pearls in enough water to cover them until tender and translucent. Drain and rinse well.
In a saucepan, cook 10g of gulaman, 1½ cups of water, and ½ cup of sugar, stirring, until the gulaman melts. Pour into a flat dish, let set, and cut into ½in / 1cm cubes.
Simmer 1 cup of dark brown sugar and 1 cup of water over medium heat, stirring, until the sugar dissolves and the syrup is clear. Let cool completely.
In a pitcher, stir the syrup into 4 cups of cold water with 1 teaspoon of vanilla extract. Spoon the sago and gulaman into tall glasses, add crushed ice, and top up with the syrup mixture.
