Salt Freshly ground black pepper Flour tortillas; warmed Place the flank steak in a shallow nonaluminum pan. Add 1.5 cups of the wine and the oil, soy sauce, 2 tablespoons of the coriander, Jalapenos, chopped garlic and the coarsely cracked black pepper. Cover and marinate in the refrigerator for at least 2 hours or overnight. Preheat the oven to 350 degrees. In a small baking dish, toast the pecans until slightly browned, about 5 minutes. Remove from the oven and set aside. Rub the remaining two whole garlic cloves with half tablespoon of the butter and roast in the oven until soft and light brown, about 20 minutes. Reduce the oven temperature to 250 degrees. In a mortar, combine the pecans, roasted garlic and Serrano chiles. Crush with a pestle. Blend in 2 tablespoons of the butter and the chives. Preheat a grill or the broiler. In a medium nonaluminum saucepan , combine the stock, remaining one third cup red wine, the vinegar, shallot, lime juice and 1 teaspoon of the coriander. Bring to a boil over moderate heat and boil until reduced to 2 tablespoons, 10 to dozen minutes. Reduce the heat to low and whisk in the remaining 2 sticks of butter, 2 tablespoons at a time. Stir in the black beans and season the sauce with salt and pepper to taste. Keep the sauce warm over simmering water. Lightly brush the flank steak with oil. Season with salt and pepper. Grill the steak over a moderately hot fire or broil until medium rare, 5 to 7 minutes. Thinly slice the steak crosswise on the diagonal and arrange on warmed plates. Spoon the sauce over each serving and accompany with warm flour tortillas. Chile Pepper Magazine