Place vegetable broth in a large pot and bring to a boil. Add sea salt and baking soda and stir to dissolve. Add corn meal in a constant stream, and bring to a boil, stirring constantly. Turn heat to lowest setting and put lid on. Let cook another 25 minutes, then remove from heat, and leave covered. Serve as quickly as possible, but stir occasionally to break up clumps and add liquid + heat to dissolve congealed polenta as need be.
While the polenta cooks, make the miso-braised kale and mushrooms.
Trim and halve cipollini onions (or slice a regularly sized onion into 1 ½-inch chunkand place in medium saucepan with 1 cup of vegetable broth and 2 tablespoons of olive oil. Bring to a simmer, then reduce heat to low, cover, and simmer until onions are translucent and tender, 25-30 minutes.
Stir in miso paste until completely dissolved, then add the black pepper and mushrooms. Stir to incorporate, then cover again and let mushrooms cook for 7-9 minutes, until tender. In last few minutes of cooking, stir in the torn kale leaves. Remove from heat and let sit, covered.
When ready to serve, dish the kale and mushrooms over the polenta, and finish with parmesan and cracked pepper.