How to Make It
Preheat the oven to 375°. On a rimmed baking sheet, toss the sweet potatoes, thyme, 1 tablespoon of the olive oil and salt. Spread in an even layer and roast for 30 minutes per side.
Meanwhile, in a large cast-iron skillet, mix 1 1/2 tablespoons of the olive oil with the vinegar, honey and molasses; season with salt. Spread the onion slices in the skillet and bake until browned, about 20 minutes per side; transfer to a plate. Reserve the juices in the skillet.
In a small saucepan, toast the cumin seeds and crushed pepper over moderate heat. Transfer to a spice mill and let cool; grind to a powder. In the same pan, heat the remaining 3 tablespoons of olive oil over moderate heat. Add the garlic and cook until golden.
Set the reserved skillet over moderate heat, add the garlic, garlic oil, orange juice and spices and simmer for 5 minutes, scraping up the browned bits from the bottom; season with salt. Mound the arugula on plates and top with the sweet potatoes and onions. Drizzle the vinaigrette over the salad and serve.
One serving 341 calories, 13.7 gm total fat, 1.9 gm saturated fat.