Add: carrots, parsnip, potatoes, chickpea and black beans to the slow cooker.
Add seasonings over top: bay leaves; cloves; peppercorn; red pepper flakes; coriander; chili; turmeric; garam masala and salt.
Top seasonings with: tomato sauce, tomato paste, vegetable stock and water.
Gently mix all the ingredients (except mushrooms) to combine making sure that most of the beans/veg are tucked under the liquid before putting the slow cooker lid on.
Cook the stew on high for about 2 hours or until the curry has thickened and taken on a deep rich color. About 20-30 minutes before serving, add the mushrooms, stirring to combine. If the sauce is thicker than you like at service time, simply add a touch more stock or tomato sauce as desired. Taste the stew and make any flavor adjustments desired (touch of salt, touch of sweet, etc).
Serve the stew in individual bowls on its own, with rice or with coleslaw/salad, as you wish. Top with green onion and/or avocado pieces, as desired.
Notes
Adding the Mushrooms towards the end: it's not a big deal if you add the mushrooms at the same time as other veg; I suggest towards the end because they will retain better texture. Similarly. if you cook this stew beyond suggested length, you can expect softer vegetables. The Carrots & Parsnip: you don't want to slice them too thin (they'll turn into mush) about ½" maybe; you can peel the parsnip before chopping if you like. Sodium Level: if you're using tomato sauces/veg stock that already contain salt, you can adjust the amount you add -- 1 tsp is a suggestion - you can start with less and move up as needed.
Recipe by Inspired Edibles at https://www.inspirededibles.ca/2018/12/curried-bean-stew-in-the-slow-cooker.html