Bring water and sugar to a boil in a small saucepan over medium-high heat. Stir in the orange zest and carrots, then reduce the heat to medium-low and simmer until the carrots are tender, 10 to 15 minutes. Drain the mixture well through a fine-mesh strainer, transfer the carrots and zest to a plate, and let them 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 surface of the rice. Place a clean, folded dish towel over the pot, then press the lid down firmly over the towel; let the rice sit off the heat for 10 minutes to finish steaming.

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