Prepare the beans. Soak the black beans overnight. Boil until just tender but still holding their shape. Drain well. Don’t overcook; they will cook again while steaming.

Soak the sticky rice. Rinse and soak the sticky rice in plenty of water for at least 4 hours or overnight. Drain well.

Cook the sticky rice. Add coconut milk, sugar, and salt to a large skillet or wok. Heat over medium until the sugar dissolves. Add the drained rice and cook, stirring often, until most of the coconut milk is absorbed. The rice should be glossy and sticky but still slightly undercooked. Let cool enough to handle.

Prepare the leaves and bananas. Thaw and wipe the banana leaves clean. For each parcel, layer an approximately 8 x 10-inch leaf with a smaller 6 x 8-inch leaf, shiny side facing outward. Peel the bananas and cut into quarters or smaller pieces.

Fill and wrap. Add a small amount of sticky rice to the center of the leaves. Top with a few black beans and a piece of banana, then cover with a little more rice and beans. Fold into a compact parcel. Don’t overfill.

Pair and tie. Make a second parcel about the same size. Place the two together and tie snugly with food-safe kitchen twine. Continue with the remaining filling.

Steam. Arrange the bundles in a steamer and steam over medium-high heat for 35–40 minutes, or until the sticky rice is completely tender. Rest for 10 minutes before opening.