Strip the peel from the grapefruit with a vegetable peeler, taking care not to include the bitter white pith. Warm the grapefruit peel, ginger, and olive oil in a small saucepan over medium heat. As soon as the oil starts to bubble, after two minutes, remove from heat. Set the oil aside to steep for thirty minutes. Strain and reserve the oil.
Meanwhile, rinse the quinoa in a fine mesh strainer. Put the quinoa in a small saucepan with one and a half cups of water, and half teaspoon of salt. Boil over high heat, then reduce heat to maintain a gentle simmer. Cook, covered, for 15 minutes. Set aside off the heat, undisturbed, for five minutes. Transfer the quinoa to a bowl, and fluff with a fork, and let cool.
Segment the grapefruit over a bowl, reserving the segments and juice separately. Also segment the orange. Whisk three tablespoons of the juice with the vinegar, honey, and salt (to taste) in a medium bowl. Gradually whisk in three tablespoons of the reserved grapefruit oil, starting with a few drops and then adding the rest in a stream to make a slightly thick dressing. Season with pepper to taste.
Toss quinoa with the dressing, minced pepper, scallions, carrots, and cilantro. Season with salt and pepper to taste.
Toss the grapefruit and orange segments into the salad. Divide among four plates. Serve warm or at room temperature.