Red tortoise cakes with sweet filling and symbolic tortoise shape represent longevity. A traditional family celebration dessert with festive red color.
Soak split mung beans in water for two hours, then steam over medium heat until tender, about 25 minutes.
Mash the steamed mung beans and mix in sugar and 1 tablespoon vegetable oil; cook on low heat for 5 minutes until you have a smooth, sweet paste.
Combine glutinous rice flour, the remaining tablespoon of oil, water, and red food coloring in a bowl; knead for 5 minutes into a soft, elastic dough.
Divide the dough into 8 pieces; flatten each into a round disc and fill with about 2 tablespoons mung bean paste, then shape into tortoise shells using a mold or by hand.
Place cakes on parchment-lined steam rack, cover with damp cloth, and steam on medium-high for 8 minutes. Remove from heat and cool before serving.