Bring two medium saucepans of salted water to a boil. Place the quinoa in one, and the red rice in the other. Lower the heat to medium, cover, and simmer until tender, about 35 minutes for the rice, and 12 minutes for the quinoa. Drain both, and spread onto rimmed baking sheets to allow to cool.
Heat 1 tablespoon of the olive oil in a medium skillet over medium heat. Add the onion and sprinkle with salt and pepper. Cover and cook, stirring occasionally, for 10 minutes, until golden brown. Set aside.
In a large bowl, whisk together the orange juice, orange zest, lemon juice, garlic, and the last 3 tablespoons of olive oil. Season to taste with salt and pepper. Add the quinoa, rice, sautéed onion, chopped apricots and pistachios, and scallions. Toss to combine. Fold in the arugua and serve.