Can you get the starchy byproduct of canned beans starting from dried beans?
Canned beans (like great northern beans or black beans) come with fluid that is thicker than water. I believe this thickening is starch being leached out of the beans into the water during the canning process. When I cook with canned beans I usually drain them and then rinse them.
A friend makes a stovetop soup by draining only some of this thick liquid, not rinsing the beans, and using relatively little additional water. She brings the pot to a boil and then covers the pot and simmers for a while. The result is a very thick broth.
My friend would like to achieve this same thickened broth (a) starting with dried beans and (b) in a slow-cooker. A slow-cooker usually does not reach a boil. Is there a way to do this without adding a different thickener to the soup, or is this effect only possible if the beans are boiled? (Yes, my friend expects to soak the dried beans first, not add dry beans directly to the slow-cooker.)