Season steaks with salt and pepper on both sides.

Let the salted steaks sit for 35 minutes in the fridge if you have time.

Heat vegetable oil in a cast iron skillet over medium high heat until almost smoking.

Sear the steaks about 4 minutes per side, or until rare to medium rare.

Remove steaks from pan and set aside to keep warm.

Deglaze the pan with water, wine, pepper, cream, brandy, and mustard (optional) and reduce to make a sauce.

Peel and cut the potatoes into about 1/4' matchsticks.

Soak potatoes in cold water for at least 2 hours.

Drain the potatoes and transfer to large bowl.

Toss with the cornstarch.

Transfer to wire rack on rimmed baking sheet or dry them on paper towels.

Heat the peanut oil to 330 degrees F.

Fry potatoes in a few batches for about 3 minutes until partially cooked, but not yet browned.

Remove each batch to drain on paper towel.

Raise the temperature of the oil to about 375 degrees F.

Fry potatoes again in batches for 1 or 2 minutes, or until golden and crispy.

Serve immediately.