1. Warm the oil in a large skillet over medium-high heat. Toss in the onions and cook for about 3 minutes, or until they become translucent. Add the garlic, green curry paste, curry powder, and salt. Give it a good stir to combine everything.
2. Pour in the broth, water, and coconut milk. Bring it to a boil, then add the lentils. Reduce the heat, cover it with a lid, and let it simmer for 30-40 minutes, stirring occasionally. This will give the lentils enough time to cook thoroughly.
3. Finally, stir in the fresh cilantro and lemon juice.