3 tablespoons vegetable oil
1 medium onion, finely chopped
1 piece fresh ginger (2 inches long), peeled and finely grated
Coarse salt
2 teaspoons curry powder
1 teaspoon garam masala (page 64; optional)
1/4 to 1/2 teaspoon cayenne pepper
1 jar (26 ounces) best-quality store-bought tomato sauce
2 cans (20 ounces each) cooked lentils, rinsed and drained
2 tablespoons fresh lime juice (from 1 lime)
1/2 cup chopped fresh cilantro, plus more for garnish (optional)
Cooked basmati (or other long-grain white) rice, for serving