In a large skillet over medium-high heat, pierce the skin of the sausages, add 1 cup of water to the pan, cover, and cook the sausages for about 10 minutes, until desired doneness.
In another skillet over medium-high heat, heat the oil and cook the peppers and onions until tender, about 5 minutes. Add the salt and pepper, stirring well to mix.
Drain the sausages and return to the pan. Over medium-high heat, add the oil and cook sausages about 5 minutes to brown on all sides.
Add the pepper mixture to the sausages to mix and heat through.
Serve on toasted hoagie rolls.