11⁄2 teaspoons dried oregano
1⁄4 cup flaxmeal
6 tablespoons shredded Parmesan cheese
1 teaspoon ground fennel seed
1⁄2 teaspoon salt
1⁄4 teaspoon freshly ground black pepper
10 ounces cremini mushrooms, finely minced
3 scallions, minced
1 large garlic clove, grated or very finely minced
11⁄4 pounds extra-lean ground turkey breast
1 large egg
To make the sauce: Pierce the sweet potato in several places with a knife. Microwave on high power for 4 to 5 minutes, until tender. When cool enough to handle, peel and cut into chunks.
Meanwhile, in a large (at least 12-inch) nonstick skillet, heat the oil over medium-high heat. Add the onion and garlic and cook until the onion is softened and beginning to brown, 5 to 7 minutes. Stir in the tomatoes, basil, and oregano. Reduce the heat to low, cover, and simmer, stirring once or twice, while you make the meatballs.
To make the meatballs: In a large bowl, combine the flaxmeal, Parmesan, fennel seed, salt, and pepper. Stir in the mushrooms, scallions, and garlic. Add the turkey and egg and use your hands to mix well. With wet hands (the mixture will be very loose and sticky), form 24 meatballs, each about the size of a large golf ball.
In a mini food processor or a medium bowl, combine the sweet potato chunks, 1⁄2 cup water, and about 1 cup of the tomato sauce from the skillet.
Process or mash to a smooth puree, then stir back into the skillet. Season with salt and pepper to taste.