Roulade of Taro Leaves with a Tomato-Mustard Sauce

I have made this dish with taro leaves (on the rare occasion when I see these Dumbo-ears-like leaves in the produce section of an Indian grocery store) and also with collard greens. The only teeny, tiny difference is in the very slightly chewy texture of the collard greens, because the leaves are a wee bit thicker than taro. But other than that, the rolls have the same incredibly complex flavors: a tart, spicy-sweet interior with the juicy succulence of tomatoes made nutty by mustard and cu