Think of this as a new riff on the Italian-American classic of sausage-and-peppers. The results rely a lot on the assertive fennel paste on the pork. Then it is a matter of timing. Don’t turn any of the vegetables or the chops until their first sides are deeply browned with the flavours of the fire.
Prepare the barbecue for direct cooking over medium–high heat (about 260°C). Brush the cooking grills clean. Place a perforated grill pan over direct heat, close the lid, and preheat for 10 minutes. Toast the fennel seeds in a frying pan over medium heat on the stove until fragrant, about 1 minute, stirring often.
Transfer the fennel seeds to a cutting board, drizzle with ½ tablespoon of the oil, and chop finely. Transfer the fennel seeds to a small bowl, add all the remaining paste ingredients including the remaining 3½ tablespoons oil, and mix to form a paste.
Coat both sides of each chop with the paste. Let the chops stand while you grill the capsicums and onions.
Lightly coat the onion slices and capsicums with oil and season with the salt and pepper.
Spread the onions and capsicums on the preheated grill pan and grill over direct medium–high heat, with the lid closed, until the onions are tender and the capsicums are charred in spots and slightly deflated, 10 to 12 minutes, turning occasionally. Remove each piece as it is done. Keep warm while grilling the chops
Grill the pork chops on the cooking grills over direct medium–high heat, with the lid closed, until well grill-marked on both sides but still juicy inside, 3 to 5 minutes, turning once. Transfer the chops to a platter and let rest for 3 to 5 minutes. Spoon the capsicums and onions and any juices around the chops and serve warm.