2 tablespoons butter
1 pound sweet potatoes, peeled and cut into 1/2-inch pieces
1 onion, chopped
1/4 teaspoon minced peeled fresh ginger
2/3 cup Arborio rice or medium-grain rice
1 cup dry Riesling wine
1/4 cup walnuts, toasted, chopped
1/4 cup chopped fresh parsley
2-3 T heavy cream (optional)
Melt butter in heavy large skillet over medium-high heat. Add sweet potatoes, onion and ginger; sauté about 5 minutes. Add rice and stir until glossy (add a bit more oil or butter if needed). Turn heat up to high and add wine, stirring until evaporated. Add hot water or vegetable stock 1/2 cup at a time, stirring each until evaporated, until rice is cooked. Season with salt and pepper, and finish by adding the heavy cream, if desired.
Spoon risotto onto plates. Sprinkle with nuts and parsley.
Note: For a less labor-intensive version involving mascarpone cheese, see the original recipe.