Remove beef and pork from cooker, using slotted spoon; place on cutting board. Strain liquid in cooker and return cooked vegetables to cooker. Shred meat, using 2 forks. Return meat to cooker. Stir in tomato paste. Increase heat setting to High. Cover and cook 10 to 15 minutes or until hot. To serve, spoon 1/3 cup meat mixture into each bun.