Preheat oven to 200C/400F
Add potatoes to a sealable food bag and add the oil, seasoning, pepper and red pepper flakes - shake the bag to coat completely
In a pan, fry the sliced sausage along with the water until most of it has evaporated, remove the sausage and let cool
Now add the sausage to the food bag. Melt butter in a pan and cook the onions and garli. Allow this to cool also and then add to the food bag
Finally, add the green beans to the food bab also and give it a shake so all ingredients are well combined. Empty the bag into a 9x13 baking dish
Cover with foil then cook in the oven for 40 minutes