Heat the olive oil in a large casserole dish over medium heat. Add the sausages and brown on all sides for 5 minutes. Remove and set aside.
Add the sliced red onion to the same pan and cook for 5 minutes until softened.
Stir in the garlic, smoked paprika and chilli flakes. Cook for 1 minute until fragrant.
Add the chopped tomatoes, tomato puree and hot water. Stir well and bring to a simmer.
Return the sausages to the pan along with the drained butter beans. Cover and simmer for 25 minutes until the sauce is thick and the sausages are cooked through.
Season with salt and pepper. Serve in bowls with crusty bread or over rice.