Blend chili powder, sugar and cornstarch in a bowl. Add ketchup and mustard and stir to combine.
Pour ketchup mixture into slow cooker and stir in 1 cup water, beans, onion and garlic. Crumble in half the turkey and gently stir to combine. Repeat with remaining turkey. Cover and slow cook on HIGH for 6 hours or on LOW for 8 hours.
Uncover and add salt. Spoon 1/2 cup of the mixture onto a roll. Top with 2 tbsp shredded cheese. Repeat, reserving any leftover mixture for another meal.
