Steak Frites with Herb Sauce and Watercress Salad
This is the dinner that makes you feel like you are eating in Paris without leaving your kitchen. Flank steak sous vide to a perfect medium rare, seared hard for a crust, and served with a herb sauce that has a touch of butter for flavor, but also lightened with yogurt. Air-fried frites don't make you feel like you are missing out.
Servings: Four
INGREDIENTS
1 1/2 to 2 pounds flank steak
1 tablespoon olive oil
1 tablespoon Dijon mustard
1 tablespoon tamari
1 tablespoon balsamic vinegar
Herb Sauce
2 tablespoons unsalted butter
1 shallot, finely minced
2 tablespoons mayonnaise
1 tablespoon Dijon mustard
1/2 c full-fat Greek yogurt
1/2 tablespoon gluten-free Worcestershire sauce
1/2 tablespoon fresh lemon juice
2 anchovies
1/2 teaspoon capers
3 to 4 fresh basil leaves
Small handful fresh tarragon
Small handful fresh parsley
4 large russet potatoes, peeled and cut into 1/4-inch fries
2 tablespoons potato starch
Avocado oil spray
4 cups fresh watercress
2 tablespoons olive oil
1 tablespoon fresh lemon juice
PREPARATION
Sous vide steak: Vacuum seal flank steak with Dijon mustard, tamari, and balsamic vinegar or place in a zip-lock bag using the water displacement method. Cook in a water bath at 130°F (54°C) for 2 hours for medium rare. Remove from bag and pat completely dry. Can be refrigerated in the sealed bag up to 3 days ahead.
Make frites: Peel and cut russet potatoes into 1/4-inch fries. Parboil in well-salted boiling water for 3 minutes. Drain and shake in the pot to rough up the edges slightly. Spread on a parchment-lined baking sheet in a single layer and freeze completely.
Make sauce: In a small pan over medium heat, melt 2 tablespoons of the butter. Add shallot and cook gently until soft and translucent without browning, about 3 to 4 minutes. Remove from heat. Stir in mayonnaise, yogurt, Dijon, Worcestershire, lemon juice, anchovies, and capers. Transfer to a blender or use an immersion blender and blend until smooth. Add basil, tarragon, and parsley and pulse until herbs are incorporated but sauce still has texture. Season with salt. Taste and adjust seasoning.
Sear steak: Let the steak come to room temperature, about 20 to 30 minutes. Heat a cast-iron skillet over the highest heat possible until smoking. Add 1 tablespoon olive oil. Season flank steak generously with salt on both sides. Sear 60 to 90 seconds per side until a deep brown crust forms. Rest 10 minutes then slice thinly against the grain.
Cook frites: Toss frozen frites with potato starch and spray generously with avocado oil. Air fry at 425°F (218°C) for 10 minutes, shake and spray some more avocado oil then air fry another 2 to 3 minutes. Season generously with salt.
Plate: Toss watercress with olive oil and lemon juice. Season with salt. Fan sliced steak across each plate. Spoon sauce generously over the top. Pile frites alongside and place a handful of dressed watercress next to the steak. Serve immediately.
Notes:
Do not season the steak before sous vide. Salt generously just before searing for a better crust and to avoid drawing out moisture during the long cook.
If you do not have a sous vide, grill or sear the flank steak in a screaming hot cast-iron skillet 3 to 4 minutes per side for medium rare. Rest 10 minutes before slicing against the grain.
Sirloin works well here as an alternative cut.
The sauce can be made up to 2 days ahead and stored in a sealed jar in the refrigerator.
