01 - Set a grill or grill pan to medium-high heat and allow it to reach full temperature before cooking.
02 - Brush the halved tomatoes, onion slices, and bell pepper with 1 tablespoon of olive oil, coating evenly on all sides.
03 - Place the sausages and oiled vegetables on the grill. Cook the sausages for 10 to 12 minutes, turning occasionally, until evenly charred and cooked through to an internal temperature of 160°F. Grill the vegetables for 4 to 6 minutes until softened and lightly charred, then remove from the grill.
04 - Let the grilled vegetables cool slightly, then coarsely chop them into bite-sized 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 frequently, until the 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 cheese if desired, then return the assembled grinders to the grill over indirect heat, cover, and cook for 1 to 2 minutes until the cheese is melted.
08 - Serve immediately while hot, garnished with additional fresh basil leaves if desired.