First make your sweet potato sauce. Using a vegetable juicer, juice 6 sweet potatoes, cut into small pieces, skin left on. Once you have enough juice, about 3 1/2 cups, let it stand for about 4 hours. This will allow much of the potato starch in the juice to settle. Trim 1 large sweet potato and cut it into hockey puck size sections. Trim sides. Rub the potato steaks with a bit of the grapeseed oil and season with salt and pepper. Place steaks on a grill pan and mark. Take your sliced filet mignon, season with salt and pepper, and sprinkle the steak fries with the Wondra flour. Transfer to a hot saute pan with tablespoon grapeseed oil. Saute steak fries until well browned and transfer to a plate lined with paper towels, and let rest for 2 to 3 minutes. Next transfer the potato steaks to a foil lined baking sheet. Bake potato steaks until tender in a preheated 350 degree oven. While the potatoes are baking, strain the sweet potato juice into a saucepan over medium heat. Reduce the sauce until you have only 3/4 cup left and the juice has naturally thickened. Stir in the chopped Thai chili, the ginger and strain the sauce. Add the chicken stock and set aside. Plate the potato steaks with the steak fries and sweet potatoes sauce. Garnish with sprigs of fresh pea shoots or watercress.