Bring the coconut milk and 1 cup water to a boil. Reduce heat to medium-low, stir in the tapioca pearls, sugar, and salt, and cook until tapioca pearls are translucent, about 30 minutes. Add banana or fresh corn kernels and cook for 10 minutes more.
Divide among 4 bowls, garnish each with a sprinkle or 2 of sesame seeds, and serve hot, at room temperature, or chilled.
Recipe courtesy of Corinne Trang, Authentic Vietnamese Cooking, Simon & Schuster, 1999