01 - Preheat a grill to medium-high heat, approximately 375°F to 400°F.
02 - Brush the halved tomatoes, onion slices, and bell pepper with 1 tablespoon of olive oil, coating evenly on all sides.
03 - Place sausages and oiled vegetables on the grill. 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.
04 - Remove vegetables from the grill and let cool briefly. Coarsely chop the tomatoes, onion, and bell pepper into uniform pieces.
05 - Heat 1 tablespoon of olive oil in a skillet over medium heat. Add the minced garlic and sauté for 1 minute until fragrant. Add the chopped grilled vegetables and season with salt, pepper, dried oregano, and crushed red pepper flakes. Cook for 3 to 4 minutes, stirring often, until flavors meld together. Remove from heat and stir in the fresh basil and parsley.
06 - Split each grinder roll lengthwise without cutting all the way through. Toast the cut sides on the grill for 1 to 2 minutes until lightly crisp and golden.
07 - Place one grilled sausage into each toasted roll. Spoon the grilled tomato sauce generously over each sausage. Top with shredded mozzarella or provolone if desired.
08 - Place the assembled grinders back on the grill over indirect heat, cover, and cook for 1 to 2 minutes until the cheese melts. Serve hot, garnished with extra fresh basil if desired.