The best is to buy the best quality meat you can find and serve less of it.
To prepare the steaks, rub them with olive oil, and sprinkle with salt and pepper. Let sit at room. temp. for at least 30 minutes.
To make the parsley sauce, place in the container of an electric food processor the parsley, lemon zest, garlic, capers, and anchovies. Process in an on/off method until the mixture is finely chopped – do not overprocess. (Alternatively, place these ingredients on a wooden board and chop with a knife or mezzaluna.) Add enough olive oil to make a moist sauce. Taste and add salt and pepper to taste.
To make the Bearnaise butter, in a small bowl with a wooden spoon mix the shallots, tarragon, and vinegar into the butter. Taste and season with salt and pepper.
To roast the potatoes, wash them and rub with olive oil. Sprinkle with salt and pepper. Place the potatoes on a baking sheet and roast at 375 degrees until tender when pierced with a fork, about 25-35 minutes.
To prepare the salad, in a bowl place the arugula or watercress. In a spoon over the greens mix 1/2 tsp. salt with the red wine vinegar, spoon over the greens, spoon over 3 Tbs. olive oil, grind on black pepper. Toss the salad and place on an oval serving plate. Place the roasted potatoes on either side of the salad.
At the last minute, grill the steak over a charcoal fire, 2-3 minutes on each side – the steak is medium rare when it feels firm but slightly resilient to the touch. Let cool five minutes on a wooden board. Slice at angles to make wide slices. Arrange the slices of skirt steak over the salad, pour any meat juices from the cutting board into the sauce. Spoon large dollops of sauce over the sliced meat and serve the rest separately (if using Bearnaise butter place in a hot oven for a moment to melt the butter.)