2 tablespoons olive oil  2 pounds 80 percent lean ground beef  1 cup ricotta cheese  2 large eggs  1/2 cup dried breadcrumbs  1/4 cup chopped fresh flat-leaf parsley  1 tablespoon chopped fresh oregano (or 1 teaspoon dried)  2 teaspoons coarse salt  1/4 teaspoon crushed red-pepper flakes  1/2 teaspoon ground fennel  4 cups Classic Tomato Sauce
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