Bring water and sugar to a boil in a small saucepan over medium-high heat. Stir in the orange zest and carrots, reduce the heat to medium-low, and simmer until the carrots are tender, 10 to 15 minutes. Drain well, transfer to a plate, and let cool.

Heat the oil in a large saucepan over medium heat until it shimmers. Add the onion and salt, and cook until the onion is softened and translucent, about 5 minutes.

Stir in the saffron and cardamom and cook until fragrant. Add the rice and cook, stirring frequently, until the edges of the grains begin to turn translucent, about 3 minutes.

Stir in the remaining water and bring to a simmer. Reduce the heat to low, cover, and simmer gently until the liquid is absorbed and the rice is tender, 16 to 18 minutes.

Remove the pot from the heat and sprinkle the candied carrots, orange zest, currants, and cranberries over the rice. Cover the pot, laying a clean, folded dish towel underneath the lid to trap steam, and let it sit undisturbed for 10 minutes.

Add the almonds and pistachios and fluff gently with a fork to combine the toppings into the rice. Season with salt and pepper to taste and serve hot.