Place onion wedges in a bowl. Use a large spoon to gently press onions until they release some of their juices. Combine oil, garlic, juniper berries, mustard, thyme, oregano, paprika, curry powder, cayenne pepper, and black pepper with onions; mix to combine.

Arrange pork chops in a large baking pan; pour marinade evenly on top. Cover and refrigerate for at least 24 hours.

Preheat an outdoor grill for medium heat.

Meanwhile, remove pork from marinade and allow to come to room temperature. Wrap onions separately in a foil pouch; discard marinade.

Cook pork steaks and onions on the preheated grill until pork is no longer pink in the center, about 10 minutes per side.