Stuffed Tomatoes with Lean Ground Beef

Preheat oven to 425 °F. In 3-quart saucepan, cook rice as label directs. Meanwhile, in 12-inch nonstick skillet, heat oil on medium 1 minute. Add onion, and cook 10 to 12 minutes or until lightly browned and tender. Stir in ground beef, half of mint, cinnamon, and 1/4 teaspoon each salt and freshly ground black pepper. Cook 5 to 6 minutes or until beef loses its pink color throughout, breaking up meat with spatula and stirring occasionally. Stir in remaining chopped mint. While ground beef cooks, cut each tomato horizontally in half. With melon baller or spoon, scoop out tomato pulp; place in large bowl. Remove 1 cup tomato pulp from bowl and chop. Discard remaining pulp or save for use another day. Return chopped pulp to bowl. Add rice, feta cheese, and beef mixture; stir until well blended. In 15 1/2" by 10 1/2" jelly-roll pan, place tomato halves, cut sides up. Mound scant 1/2 cup beef filling in each tomato half; sprinkle with panko. Bake tomatoes 25 to 30 minutes or until crumbs are browned and filling is heated through. Garnish with mint sprigs.