Pour the oil into a large skillet over medium heat and add the onion and ginger. Cook for 2 to 3 minutes, or until the onion is soft and then add the cumin seeds, mustard seeds, and curry leaves and toast for 10 seconds. Add the grated turnip, green onion, and salt. Reduce the heat to medium-low heat and cook for 5 minutes, stirring regularly.
Clean the lettuce and separate the leaves. Put about 1/2 cup of turnip mixture into a leaf and add some chutney. Wrap the lettuce around the mixture and enjoy.