In a heavy, wide, lidded pan, melt butter over medium-low heat. Add onion, red pepper, and kosher salt. Sweat the onions and peppers until aromatic, stirring constantly. Add the rice and stir to coat. Continue stirring until rice smells nutty. Add chicken broth, orange zest, saffron and water, and bay leaf. Bring to a boil. Stir once, then cover pan with moistened dish towel (or tea towel). Place lid on pan and fold towel corners over lid. Bake for 15 minutes. Then rest at room temperature for 10 to 20 minutes without removing the cover.
Meanwhile, simmer peas in salted water until heated through or heat in a microwave.
Remove lid from rice and turn out onto a platter. Add peas and fluff with a large fork. Add raisins and pistachios.