In a small bowl, combine the tapioca starch and ¼ cup of the rice milk and mix to form a paste. Set aside for 10 minutes.
In a large saucepan, combine the remaining 3 cups rice milk, and1 ¾ cup coconut milk with the rice, cardamom, cinnamon stick, sugar and tapioca mixture. Bring to a boil over medium-high heat, stirring frequently. Lower the heat to maintain a high simmer and cook, stirring occasionally, until the mixture has reduced by about two thirds, about 30 minutes to an hour.
Fish out and discard the cardamom pods & cinnamon stick. Add the rose water, saffron, salt and soy lecithin and stir briefly to combine. Transfer to a bowl, cover with plastic wrap and refrigerate until well combined, at least 1 hour and up to overnight.
To serve, spoon the pudding into 4 individual bowls and garnish with the pistachios.