You have to use some kind of liquid to cook dried beans, whether it's water, broth, stock, beer, etc. Beans absorb water when they cook, besides all the water they have absorbed while soaking.
Frankly, I don't know how Bliss's recipe works. If it works for her as posted above, i.e. no additional liquid, that's great, but every other recipe I've found from sites I trust, calls for added liquid of some kind so that the beans would have liquid to absorb. I've used dried Great Northerns in other types of recipes and they ALL have called for what you would think is excess liquid because the beans absorb some and some evaporates away while cooking.
I suspect you either got a bag of old beans that would need pressure cooking to soften, or the long, under temperature cooking they were subjected to somehow caused the skin to harden so the beans couldn't absorb liquid.
Oh, and you certainly don't add cornstarch while beans are cooking regardless. Doing that thickens the liquid too much and they are never going to absorb it.
All those extra sugary things that were added didn't help much either. The extra sugars probably hardened the skin even more.
This kind of reminds me of when my friend's husband, who really didn't cook, decided to make chili while she was at work. He followed her slow and low cooking recipe, with lots of liquid at the start, but tasted it shortly after it started cooking and felt it didn't have enough kick or salt, so added more salt and more chile powder. Did that a couple more times, then decided it was good. By the time it finished cooking a couple of hours later, it was inedible because of the salt and spice...
www.discusscooking.com
