I grow sweet potato for leaves here in Seri Kembangan, Selangor. I've harvested many time, normally I stir fry. The plant is so easy to grow..the more you harvest the leaves, the more it grows back to more leaves.. I stir fry sweet potato leaves (sometimes add belacan or dried shrimp), masak air/watery soup (no oil used, just dump leaves in boiling water, add also seasonings) or masak lemak (cooked in coconut milk) with chunks of sweet potato tubers or pumpkin added, little shrimps added too..
I love this ching chao style and always wanted to learn how to cook it. Sweet potato leaves is lots of work and even after painfully stringing the stems of baby sweet potato leaves, can still be fibrous. Ah, maybe i can substitue with baby spinach and same style.