To make the caramelized onions, heat the oil in a medium non-stick skillet over medium heat.
Add the onions and salt; cook, stirring frequently, until the onions are very soft and brown, about 20-25 minutes.
Meanwhile, combine the broth, lentils, garlic, ginger and curry powder in a large skillet over high heat; bring to a boil.
Reduce the heat and simmer, covered, about 15 minutes.
Stir in the carrots; arrange the broccoli and cauliflower in a single layer over the lentils.
Bring to a boil; reduce the heat and simmer, covered, until the lentils and vegetables are tender, about 10-15 minutes.