Preheat the Grill or Skillet: For the grill, preheat to medium-high heat.
If using a skillet, heat it over medium-high heat.
Prepare the Sausage and Vegetables: In a mixing bowl, combine the sliced bell peppers, onions, minced garlic, olive oil, salt, black pepper, dried oregano, dried basil, and red pepper flakes (if using). Toss until well coated.
Grill or Sauté the Sausage: If grilling, place the sausage links on the preheated grill. Cook for 15-20 minutes, turning occasionally until they are cooked through and have a nice grill marks.
If using a skillet, add the sausage links and cook over medium-high heat until browned on all sides and cooked through.
Cook the Peppers and Onions: While the sausages are cooking, spread the seasoned peppers and onions on the grill or in the skillet. Cook until they are softened and slightly charred, stirring occasionally. This should take about 10-15 minutes.
Assemble and Rest: If using hoagie rolls, split them and toast them on the grill or in the skillet.
Place the cooked sausages in the rolls and top with the grilled peppers and onions.
Optional: Add cheese slices on top and allow them to melt.
Let the assembled sausages and peppers rest for 5 minutes to allow the flavors to meld.
Serve: Garnish with chopped fresh parsley.
Serve hot, optionally with additional condiments like mustard or marinara sauce.