Heat 2 Tbs. of the oil in a 10-inch straightsided sauté pan over medium-high heat. Add the onion, scallion whites, saffron, red pepper flakes, and a generous pinch of salt. Reduce the heat to medium and cook, stirring occasionally, until the onion is tender and golden brown, 7 to 8 minutes. Stir in the remaining 2 Tbs. oil, the garlic, and cinnamon and continue to cook for 1 minute more. Add the couscous and 1-1/2 tsp. salt and stir constantly until the couscous is lightly toasted (the color will turn a light brown), 2 to 3 minutes. Remove from the heat.
In a small saucepan, bring 2 cups of water to a boil over high heat. Add the water to the pan with the couscous, stir to combine, cover, and cook at a simmer over medium-low to low heat until the couscous is tender and has absorbed all of the liquid, about 10 minutes.
Add the pine nuts, currants, and parsley and toss to combine. Season to taste with more salt if necessary. Transfer to a platter or distribute among individual plates, sprinkle the scallion greens on top, and serve.