Preheat the fryer. In a blender, combine the stock, mustard, watercress and parsley. Puree until smooth. Season with salt and pepper. Strain the sauce through a fine mesh strainer. Pour into a saucepan and place over low heat, keep warm. Fry the potatoes until golden brown. Remove and drain on paper towels. In a saute pan, over medium heat, add 2 tablespoons of the oil. When the oil is hot, add the shallots, garlic and morels. Season with salt and pepper. Saute for 3 to 4 minutes, or until the morels are tender. Add the potatoes and continue to saute for 1 minute. Remove from the heat and keep warm. Season both sides of the bass with salt and pepper. In a large saute pan, over medium heat, add the remaining 3 tablespoons of oil. When the oil is hot, pan-fry the bass for 3 to 4 minutes on each side. Remove from the pan and drain on paper towels. To serve, spoon the sauce in the center of each plate. Spoon some of the mushroom/potato mixture in the center of the sauce. Lay the fish on top of the mushrooms. Garnish with chives.