In a medium saucepan heat oil and cook the onions over moderate heat, stirring occasionally, until they become translucent. Add garlic and bell peppers and cook, stirring, for 5 minutes
Add all remaining ingredients and bring the liquid to a boil. Turn down heat simmer the stew, stirring ocassionally, for 45 minutes.
Add the kale and cook another 5 – 10 minutes just until the kale wilts.
Season with salt and pepper.
Serve the stew on the couscous or rice, with a dollop of yogurt if desired.