1. In a large bowl, combine the beef, chorizo, and spices through chopped parsley. Mix gently by hand until well incorporated, then form into 6 equal patties. Set aside, chilled.
2. Heat grill to medium high heat. In a small grill-proof saucepan, heat evaporated milk until simmering. Remove and whisk in provolone cheese and sambal; set aside to keep warm.
3. In another small saucepan, bring onion, vinegar, sugar, and salt to a boil; remove and set aside to pickle.
4. Place burgers on grill, and cook until medium, 3-5 minutes per side. While burgers are cooking, brush buns with melted butter and toast on both cut sides.
5. Combine nappa cabbage, cilantro, celery seed, and the
quick-pickled red onion in a bowl.
6. To assemble, place burger on bottom bun, pour about 1 Ounces of cheese sauce on top, top that with nappa slaw, and finish with the top bun.