To begin, wash the banana leaves thoroughly. Pass each leaf briefly over an open flame or a hot dry pan to soften them and prevent tearing. Cut into rectangles about 25 cm by 20 cm. Move to cooking the rice mixture.
Drain the soaked glutinous rice. In a heavy pan, combine coconut milk, brown sugar, and salt. Stir over medium heat until the sugar dissolves and the mixture just starts to simmer. Proceed to the next step quickly before the coconut milk thickens.
Add the drained rice into the simmering coconut mixture. Stir continuously until most of the liquid is absorbed and the rice is half cooked, about 10 minutes. The grains should still be firm. Transfer to a plate to cool slightly before wrapping.
Lay one banana leaf flat. Place about 4 tablespoons of the coconut rice mixture on the centre. Shape into a log about 10 cm long. Move to wrapping.
Fold the banana leaf lengthwise over the rice, then fold the ends securely to form a neat parcel. Tie with kitchen twine if necessary. Repeat with remaining rice. Move to steaming.
Arrange the wrapped suman in a steamer basket. Steam over medium heat for 45 to 50 minutes, or until the rice is fully cooked and tender. Transition to cooling before serving.
Once cooked, remove the suman from the steamer and allow to cool slightly so the flavours settle and the parcels firm up. Proceed to serving.
Serve warm or at room temperature. Traditionally enjoyed on its own, suman is often paired with fresh mango or sprinkled with grated coconut for added richness. Presentation tip: Serve in the leaf for an authentic rustic look.