This time I put the dry beans in cold water and vaguely rubbed them through my fingers. Same as last time, but the idea is to hopefully release and rinse away some of the oligosaccharides, which won't happen between the soak and cook stages this time, so it was extra important to get that quick rinse in up-front.
Drained and put them on heat with 3 cups of fresh water, and a couple shakes of salt for the soak. Brought to a low boil, covered and removed from heat. Popped a pint of SR and let the beans soak and cool 1 hour. This still resulted in about 2 cups of bean broth.
Drained broth off to a separate container, rinsed soaked beans, sampled the broth, added remaining broth back (SR working its magic, best not to question), mixed in a cup each of frozen chopped spinach and broccoli cuts (not crowns, Birds Eye was on sale if you must know). Added another 2 cups water to cover the lot, plus ~4 shakes of salt. Brought to a boil and cooked 45 minutes.
Unsurprisingly, the beans absorbed most of the added liquid. Also unsuprisingly, in the absence of boullion, this came out a good deal less salty and the umami component more subtle. The lentils were pretty much disintegrated, but the rest of the beans kept a nice tender-to-chewy texture. When the current bean mix baggies run out, I think I'm going to reboot the procedure, keeping lentils separate until after the soak.
Very pleased with the results, overall. Between minimizing water addition, retention of broth from the soak stage, and addition of frozen greens, the end product is much more flavorful than round 1. I'm not missing the heavy-handed beef broth theme from round 2. I'm also not regertting the substitution of broccoli cuts instead of crowns, as crowns are mostly indistinguishable from the spinach after 30-45 minutes of cooking.
Pearl onions or shallots; capers; herbs like dill, thyme, maybe rosemary, but almost certainly not sage; and/or replacing the soak stage water with white wine - all twists I have to try now that I'm satisfied with the basic prep.
On a side note, the Wikipedia article for "umami" notes that tomatoes are rich in compounds that impart umumi flavor, and I suspect that's why tomato juice is so uniquely satisfying.