Slow Cooker Barbecue Pulled Chicken

One 14.5-ounce can no-salt-added diced tomatoes, plus their juices
1/4 cup apple cider vinegar
2 tablespoons honey
1 tablespoon Spanish smoked paprika (pimenton)
1 tablespoon soy sauce
1 tablespoon Dijon mustard
1/4 teaspoon crushed red pepper flakes, or as needed
2 pounds boneless, skinless chicken breast halves (4 halves)
Coarse kosher salt
Freshly ground black pepper
Hamburger buns or rolls, for serving
Sweet and Tangy Barbecue Sauce (see related recipe),
 or your favorite barbecue sauce, for serving

Combine the tomatoes and their juices, the vinegar, honey, paprika, 
soy sauce, mustard and crushed red pepper flakes in the insert of 
your slow cooker. Add the chicken and season well with salt and 
pepper. Cover with the lid and cook on LOW for about 5 hours, or 
until the chicken is falling apart.

Taste, and add more salt and/or pepper. Spoon onto buns or rolls 
and serve hot, with barbecue sauce on the side.