In a large deep frying pan, heat a glug of oil and add the sliced sausages. Fry for 5 minutes, turning every now and then, until golden brown.
Add the onions to the pan (you may need some more oil). Fry for 5-8 minutes until softening then turn up the heat and add the garlic, rosemary and vinegar, then cook for 2-3 minutes more.
Add the spinach, a splash of water and the beans then fry for another 5 minutes. Add the creme fraiche and cook for a minute more until all the spinach has wilted and the sausages are cooked through. Adjust seasoning to taste and serve.