Boil a large pot of water and add cabbage leaves. Reduce heat to medium. Cook, covered, until tender but not mushy, about 10 min. Drain and rinse with cold water. Transfer to a kitchen towel and pat dry.
Boil broth in a medium sauce-pan, then add bulgur. Reduce heat to medium. Cook, covered, until bulgur is tender and liquid has been absorbed, about 6 min. Set aside.
Melt butter in an extra-large frying pan over medium-high. Add mush-rooms, onion, garlic, oregano and 1/4 tsp salt. Cook, stirring often, until onion is soft, 4 min. Crumble in turkey. Cook until meat is no longer pink, about 5 min. Remove from heat. Stir turkey mixture into bulgur.
Stir passata with sugar and remaining salt in a medium bowl. Spread 1 cup of sauce on the bottom of extra-large frying pan. On a clean work surface, place a heaping ½ cup turkey filling in the middle of a cabbage leaf. Fold each end in to–ward centre, then roll up. Arrange seam-side down in pan. Repeat with remaining leaves and filling.
Spread remaining sauce over cabbage rolls. Return to stovetop set over medium-low. Cook, covered, until warmed through, about 5 min.
Serve and enjoy!