Set sous vide machine to 55C/131F.
Salt and pepper the rib eye to taste. Put the steak in a freezer bag with crushed garlic and rosemary, and remove the air through a vacuum sealer or the displacement method. Drop steak in the bath for 1 1/2 hours.
Remove steak from bath. Pat dry with paper towels. Heat pan on high and add oil. Sear for 60-90 seconds on each side. Remove from pan and let rest for 5 minutes
Heat large skillet over medium-high heat, and pour in oil.
While oil is heating, peel the potato and slice it in to french fry sticks.
In a gallon sized zip-lock bag, mix the flour, paprika, salt and pepper. Gradually stir in water until the consistency of the mixture is thin drizzle from a spoon. Place potato sticks into the bag and shake the bag until the fries are evenly coated.
One at a time, place the potato sticks in the the hot oil, ensuring that they do not make contact with one another. Fry until golden brown and crispy. Remove fries with slotted spoon and place on towel-lined plate.
In a small cup, mix mayonnaise, dijon mustard and whole grain dijon mustard. Serve fries with sauce and enjoy a delicious and traditional French dish.
If you cut potatoes before they are ready to be battered and fried, make sure to place them in a bath of cold water so they do not brown.