Melt butter in a heavy 2 quart saucepan over medium-high heat. Add onion and saffron; sauté until onion is golden. Add apricots and rice; continue to sauté until rice becomes opaque.
Add water and salt. Bring to a boil; reduce heat to low and simmer covered 15 to 20 minutes, or until all liquid is absorbed and rice is tender. Fluff with a fork.
To serve, place rice in desired serving dish and garnish with pistachios.