Is there a way to make leafy green vegetables absorb salt throughout their tissue? For example you can make protein tissue absorb salt by brining/dry curing it.  What ways can I make say some spinach or kale tissue absorb salt?  I want the salt to be in and throughout the greens and not just placed on the surface.
Also if there is any penetration, I take it, it is just on the leaf parts and won't go into the stalk?
When the greens are cooked, the cells will rupture and more easily take on outside fluids (and salt), so salting them while cooking will get the salt into the greens. You could also brine or rub the leaves with salt, this is frequently done with cabbage before pickling. The effectiveness of this method will vary depending on the greens though, some leaves like kale have a more waterproof layer over the outside of the leaf, so just rubbing them with salt may not work. I have seen people "massage" the leaves with salt to tenderize them and break down some of the fibers, or blanch them in salted water.