1 ½ pound steak (Portehouse or Rib Eye, preferably) cut into 1 ¼-inch cubes
oil (for frying)
4 bamboo skewers (soaked in water at least 20 minutes)
1 tablespoon minced mixed herbs (optional as garnish)
Make the sauce: Place a medium saucepan over medium heat and add 1 tablespoon butter and the shallots. Season with salt and pepper and cook until the shallots are softened, but not yet colored, about 3 minutes. Add the vinegar and cook, stirring occasionally, until it evaporates, then add the wine. Let the wine come to a boil then lower the heat and let the sauce reduce by about half. Remove the pan from the heat and stir in the remaining butter; set aside.
Prep the potatoes: Scrub the potatoes, peel them if you like, then slice them lengthwise into slabs, 3/8 inch thick. Cut the slabs lengthwise into 3/8-inch batons. Place the cut potatoes in a bowl filled with cold water to rinse off some of the excess starch and prevent discoloration. Potatoes may be cut up to a day in advance if they are left in water and stored in the refrigerator.
Prep the steak sticks: Place the steak cubes in a medium bowl; toss with a big pinch or two each salt and pepper. Thread the cubes divided evenly onto the 4 prepared skewers. Don’t squeeze them together too tightly. Leave room for the edges to char. Set aside.
Give the potatoes their first fry: Preheat the oil in a deep fryer (or tall, deep sided stock pot) to 325 degrees. Line a sheet pan with paper towels to absorb the oil from the cooked potatoes. Pour the potatoes from their water filled bowl into a colander then pat them completely dry with paper towels. Fry the potatoes in several batches to avoid crowding the oil, stirring them to distribute evenly in the oil until they just begin to turn golden, about 4 to 5 minutes. Move the par-cooked potatoes to the paper towel lined sheet pan and let them come to room temperature, at least 10 minutes and up to an hour before serving time. Raise the temperature of the oil to 365 degrees.
Grill the steak sticks: Heat grill to high. Grill the meat on the skewers for 2 to 3 minutes per side until charred on the outside and cooked to medium-rare on the inside (or to your desired doneness). Move to a platter, cover loosely with foil and let the meat rest while you finish the frites.
Give the potatoes their second fry: Working with about half the potatoes at a time, fry in the 365 degree oil until golden brown and crisp, about 4 minutes. Drain them on a paper-towel lined baking sheet; toss with kosher salt.
Gently reheat the sauce and place into a serving vessel. Serve the frites and steak together; garnish with minced herbs (optional). Serve the sauce on the side for drizzling.