Soak moong dal in water for half an hour.
Peel the ridgegourd and save the peels. Make sure you remove the ribs and discard.
Chop the peels.
Put 2 tablespoonfuls of oil and put a red chili. Then add mustard seeds. When they start spluttering, add chana dal, urad dal, jeera, turmeric, green chilies, ginger and curry leaves. Then add the chopped vegetable peels and salt to taste.
Cook on low to medium flame for about 5-8 minutes, add salt. When the peels are soft, add the soaked moong dal and cook for another 8- 10 minutes. When the dal is cooked rest for 10 minutes. Now add lemon juice.