I am 99% sure that "empty heart" is Kang Kong aka Tai Water Spinach, latin name (ipomoea aquatica) it has dozens of common names. We grow it here in Texas (technically illegal because they say it is invasive). It is not invasive in north Texas where I live. It doesn't over winter. It is actually in the same family as sweet potato.

The blood cake looks very similar to "black pudding" which is a big part of an Irish Breakfast. They use oats instead of rice but it seems almost the same. I love that stuff.