Tips of hamburg rooted parsley show their greens.
-- edited to include a new link - check it out.--
If you don't want to set a coldframe or polytunnel to winter greens, you can set up a cellar. Still sound like work? Okay, lots of roots store for quite some time at the back of the fridge. When you are ready to eat some fresh leaves, take out these roots, put them in a pot of moist sand and stick them some place warm. You can even eat part of the root and still get a harvest. These 'carrot' rooted parsley sprouts are coming out of about a quarter inch of crown at the top of the root that is placed in a shallow dish of water. That's enough parsley for most recipes - not tabouleh; I would have had to save a couple inches more root for that.
Greens of certain plants are bitter such as chicory. To make sweeter, more tender shoots, force in darkness. Chicons, sold in supermarkets as Belgian Endive are made from varieties of chicory such as Witloof de Brussels.
Here some roots to force for edible greens:
2. Hamburg Parsley
3. Celariac - strongly flavoured, try dark forcing or use sparingly
Other good candidates may be found in plants with edible greens / shoots that have roots that can be lifted and stored with relative ease. If you have a suggestion, add it in the comments. I'd love to try it.
* My research leads me to believe that eating carrot greens is good for you but they are a bit fiborous so there are various mentions of 'juicing' them. With new or marginal food, always do lots of triple checking and start with a small amount first.
** Don't eat regular potato Solanum tuberosum greens as they contain poisonous alkaloids which is why your mom always told you to cut the green parts off.
Harvest Day Roots of Fall
Eliot Coleman author of books about season extension and organic market gardening. Most libraries carry various titles.
High Desert Garden has a lovely post with great pictures of growing garlic shoots.