Coconut and Red Lentil Curry

adapted from epicurious.com

1 medium onion, finely chopped
2 tablespoons vegetable oil
1 tablespoon finely chopped peeled fresh ginger
2 garlic cloves, finely chopped
1 teaspoon ground cumin
1/2 teaspoon ground coriander
1 teaspoon turmeric
1 teaspoon salt
1 cup water
1 cup vegetable broth
1 1/2 cups dried red lentils (10 oz)
1 (13- to 14-oz) can unsweetened coconut milk

Cook onion in oil in a 3 1/2- to 4-quart heavy pot over moderate heat, stirring occasionally, until edges are golden, about 6 minutes. Add ginger and garlic and cook, stirring, 1 minute. Add cumin, coriander, turmeric, salt, and cook, stirring, 1 minute.

Stir in water, lentils, and coconut milk, then simmer, covered, stirring occasionally, 5 minutes. Simmer, covered, until lentils are tender about 15 minutes. Season with salt and serve with cilantro sprigs scattered on top.