Preheat oven to 350°F. In a small bowl, combine cumin, salt, ginger, turmeric and pepper. Pat roast dry with paper towels and rub all over with seasoning mixture.
In a large Dutch oven or oven-proof heavy saucepot, heat olive oil over medium-high heat. Add roast and brown on all sides. Remove to a plate and set aside. Add onions and 1/4 cup water and cook about 8 minutes or until tender and golden, stirring occasionally.
Stir in broth and juice and bring to a boil. Add roast back to pot, cover and transfer to oven. Roast 2 hours.
Stir in potatoes and carrots, cover and continue roasting 45 minutes longer or until vegetables and meat are tender. Transfer roast and vegetables to a large serving platter and drizzle with pan juices.
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