profligate - help me reform (leeks)
Color and fibrousness tend to go hand in hand, but one isn't an absolute indicator of the other. As you're slicing the leeks, pop a bit of the green stuff in your mouth. If it's tender, no worries. If it's tough, use it for stock or other application where the fiber will get strained out.
I left part of the green part on (trimmed the roots) then split and rinsed the leeks and braised the halves in olive oil and chicken stock. Then took them out of the pan and reduced the braising liquid (remember to add any that comes off the leeks while resting) for use as sauce plus a mustard based vinaigrette to serve them room temp. They were pretty good.
Leftovers would probably make a decent sandwich or frittata.
I haven't tried this, but it might be worth the experiment of slicing them super-thinly, crosswise, then steaming them. I'd then add them to a stir-fry or pour Italian or vinaigrette dressing over them, let them marinate in it, then taste at room temperature or chilled. Or, after very thinly-slicing, add to a long-simmering soup or spaghetti sauce.
Once I tried a recipe where I used them as wrappers around a smoked salmon filling. It was a lot of work and only okay so I haven't done that again! I haven't found any other use for them fresh. Now I throw all of mine into a ziploc bag and put them in the freezer. Then I use them to make broth.