Submerge in the water oven to cook for at least 2 1/2 hours and up to 4 hours.
In the last 30 minutes of cooking time, add the pouch of cooked green beans to the water oven to reheat.
Remove the fillets, pat dry with paper towels.
On the stovetop, in a skillet over high heat, add the vegetable oil and when very hot, sear the filets on one side for a minute, then flip them and add the butter and remaining sprig of rosemary to the pan. Baste the meat with the butter for another minute for form a mahogany crust on both sides. Roll the edges of the filet in the hot skillet if you like to brown them.