Place sweet potatoes and 1/3 cup water in a large microwave-safe bowl. Cover with plastic wrap and microwave at HIGH 15 minutes or until potatoes are tender. Carefully uncover; drain and keep warm.
Heat oil in a large nonstick skillet over medium-high heat. Remove casings from sausage. Add onion to pan; sauté 6 minutes or until tender. Add sausage and 1/4 teaspoon salt; cook 4 minutes or until sausage is done, stirring to crumble. Stir in sweet potatoes, 1/2 teaspoon salt, syrup, 1 tablespoon water, pepper, and nutmeg. Cook until liquid is absorbed and sweet potatoes begin to brown (about 5 minutes).