01 - Set your grill to medium-high heat and allow it to reach a consistent temperature before cooking.
02 - Brush the halved tomatoes, onion slices, and bell pepper strips evenly with 1 tablespoon of olive oil.
03 - Place sausages and oiled vegetables on the grill simultaneously. Cook sausages for 10 to 12 minutes, turning occasionally, until evenly charred and cooked through to an internal temperature of 160°F. Grill vegetables for 4 to 6 minutes until softened and lightly charred, then remove from heat.
04 - Allow grilled vegetables to cool briefly, then coarsely chop them into bite-sized pieces.
05 - Heat 1 tablespoon of olive oil in a skillet over medium heat. Add minced garlic and sauté for 1 minute until fragrant. Add the chopped grilled vegetables, season with salt, pepper, dried oregano, and crushed red pepper flakes. Cook for 3 to 4 minutes, stirring frequently, until the flavors meld together. Fold in the fresh basil and parsley.
06 - Split each grinder roll lengthwise without cutting all the way through. Place cut-side down on the grill and toast for 1 to 2 minutes until lightly crisp.
07 - Place one grilled sausage into each toasted roll. Spoon the grilled tomato sauce generously over each sausage. Top with shredded cheese if desired, then return to the grill over indirect heat, cover, and cook for 1 to 2 minutes until the cheese melts.
08 - Serve immediately while hot, garnished with additional fresh basil leaves if desired.