Pour the vegetable oil into a frying pan and add the sliced onion and cook over a medium heat for a few minutes until softened.
Add the garlic, paprika and thyme and continue to cook for a further minute. Increase the heat.
Pour in the brown ale and allow to bubble and reduce, sprinkle over the flour and stir well over a low heat. Add the puree, tomatoes and stock.
Pour into the slow cooker bowl along with the squash and sweet potato, stir well and cover with the lid. Cook on Low for 6 hours or High for 4-5 hours.
Add the kale and beans 1 hour before the cooking time has elapsed.