01 - 
                Heat olive oil in a skillet over medium-high heat. Brown the sausages on all sides for about 2 minutes per side. They should not be cooked through.
              
              
              
                02 - 
                In the slow cooker, combine sliced peppers, onions, minced garlic, Italian seasoning, salt, and pepper. Toss everything to coat evenly.
              
              
              
                03 - 
                Pour the marinara sauce evenly over the vegetable mixture. Place the browned sausage links on top.
              
              
              
                04 - 
                Cover and cook on Low for 4-5 hours or on High for 2-3 hours, until sausages are fully cooked and vegetables are tender.