Sausage, Peppers and Onions

• 16-20 oz. Italian sausage (I use Jennie O Hot Italian Turkey Sausage)
• 2 onions thinly sliced
• 2 bell peppers (red, orange or yellow) thinly sliced
• 2 tbls. Olive oil
• 1 tbls. Balsamic vinegar
• 1/4 tsp. sea salt
• 1/8 tsp. freshly ground black pepper
• 1/8 tsp. crushed red pepper