Place onion wedges and chicken broth in slow cooker.
In a small bowl, combine parsley, 5 cloves minced garlic, vinegar, 1 tablespoon lemon juice, cumin, dried mustard, oregano, ½ teaspoon salt and ½ teaspoon pepper. Rub over pork.
Add pork to slow cooker. Cover and cook on low 6-8 hours until meat is tender.
Take meat out of slow cooker and let stand 10 minutes before slicing.
In another small bowl, combine mayonnaise, Dijon mustard, remaining 2 cloves minced garlic and 1 tablespoon lemon juice; spread over buns.
Layer bun bottoms with pork, cheese, sliced sweet onion and pickles; replace tops.
Cook on a panini maker or indoor grill until buns are browned and cheese is melted, 2-3 minutes.