In a medium sized mixing bowl, mash the bananas with a fork, leaving it a bit chunky.
300 g peeled ripe bananas
In a small mixing bowl, combine the rice flour, tapioca starch, sugar, salt and whisk to combine. Add the coconut milk and whisk until smooth, then add most of the shredded coconut, holding back about 1½ tablespoon for garnish, and stir to mix.
30 g Thai rice flour, 25 g tapioca starch, 30 g granulated sugar, 2.5 ml table salt, 120 ml coconut milk, 120 ml dried shredded coconut
Pour the batter into the bananas and mix until well combined. Taste the batter, and if you want it a little brighter, you can add the lime juice, or you can add more sugar as well if you want it sweeter.
¾ teaspoon lime juice
Preheat the steamer by bringing the steaming water to a full boil. Meanwhile, drizzle your reserved coconut with roughly a teaspoon or so of hot water (which you can take from the steamer) to rehydrate; this will help the coconut shreds stick together and it’ll make a nicer mound of garnish on top of the cakes.
Fill your containers, leaving a ¼ inch or so of headroom to allow for expansion. Garnish with the rehydrated coconut.
Steam the cakes over boiling water until internal temp reaches 200°F (93°C). For cupcake size, it’ll take 18-20 minutes. Increase or decrease the time according to the size of your container and thickness of the batter. When in doubt, steam them for longer because nothing bad will happen if you over-steam them a bit. But do make sure you’ve got enough water in the pot so it doesn't dry out and burn the pot!
Allow to cool until warm or room temp before eating, as it'll be too soft right out of the steamer. Keep in the fridge for up to 1 week, or freeze. Reheat in the microwave, making sure to heat them until steaming hot to regain the soft texture.