Add all of the ingredients except for the crushed red pepper and flour to the slow cooker. Cover and cook on low for 8-10 hours. If you like your kale to have more bite to it, add it during the last hour of cooking. About an hour before serving mix the 1 tablespoon of flour with 1 tablespoon of water and stir into stew. At this time you can also remove the thighs and when cool, shred the meat from the bone and return to the stew.
Taste and add salt and pepper if necessary.
Serve garnished with crushed red pepper flakes.
Video
Notes
Can use onions if you can't find leeks.Chicken thighs are best, but you can use your favorite parts. Bone in, skin on adds more flavor.