- 1 (1 3/4-lb) head cauliflower, cut into 3/4-inch-wide florets
- 1 1/4 lb Yukon Gold potatoes, peeled and cut into 1/2-inch cubes
- 5 tablespoons vegetable oil
- 1/2 teaspoon cumin seeds
- 3/4 teaspoon salt
- 1 medium onion, finely chopped
- 2 garlic cloves, finely chopped
- 2 teaspoons minced fresh jalapeño, including seeds
- 2 teaspoons minced peeled fresh ginger
- 1 teaspoon ground cumin
- 1/2 teaspoon ground coriander
- 1/4 teaspoon turmeric
- 1/4 teaspoon cayenne
- 1/2 cup water
- Accompaniment: lemon wedges
- Put oven rack in upper third of oven and place a shallow baking pan on rack. Preheat oven to 475°F.
- Toss cauliflower and potatoes together in a bowl with 3 tablespoons oil, cumin seeds, and1/4 teaspoon salt. Spread in hot baking pan and roast, stirring occasionally, until cauliflower is tender and browned in spots and potatoes are just tender, about 20 minutes.
- While vegetables are roasting, cook onion, garlic, jalapeño, and ginger in remaining 2 tablespoons oil in a 12-inch heavy skillet over moderate heat, stirring frequently, until very soft and beginning to turn golden, 8 to 10 minutes. Add ground cumin, coriander, turmeric, cayenne, and remaining 1/2 teaspoon salt and cook, stirring constantly, 2 minutes. Stir in water, scraping up any brown bits from bottom of skillet, then stir in roasted vegetables. Cook, covered, stirring occasionally, 5 minutes.