Spigariello Liscia (Broccolo Spigariello or Brassica oleracea var. 'Spigariello') is an heirloom Italian leaf broccoli that is less bitter than raab. It's claimed to be cold hardy down to 25 F after seedlings are established, but mine overwintered a few years ago and then burst into bloom and produced seeds. I'm sure we went below 25 at least a few times!
Broccoli (Brassica oleracea 'Spigariello')
Tasoi is very cold tolerant - allegedly down to 15 F once established. Like a ruffled Bok Choy with no stems (a low rosette). It doesn't grow as fast as Bok Choy, and is more for salad than soup.
Tah Tsai (Brassica rapa subsp. narinosa 'Tatsoi')
'Tyfon' or Holland Greens are even more cold hardy - allegedly down to 10 F once the seedlings are established. It's VERY productive and very mild - so much so that boiled greens have only the flavor of what you cook them with! They are a stabilized cross between stubble turnips & Chinese cabbage, so you can save your own seeds.
Holland Greens (Brassica rapa 'Tyfon')
