While simultaneously having an insatiable craving for sandwiches and a desire to cut back on all but the healthiest of oils, I encountered a lack of sandwich lubricating options. Most are familiar with the almost unsurpassable avocado option, but I wanted a few fat-free selections so experimented with two, both of which I think are permanent additions to my sandwich repertoire: eggplant and sweet potato.
For the eggplant, I pop the whole thing in the oven and bake it until completely soft. Separate the insides from the peel and let drain in a colander, stir it up with a fork and spread it on both slices of bread. I had mine with rustic whole wheat bread and a tofu, wild-rice burger.
The sweet potato version you pretty much make the same way: bake, mash, spread. This one is really good with a few dried cranberries or dried tart cherries thrown in.