Heat oven to 400°F. Place sausages in roasting pan; rub sausages with oil. Roast 15 minutes.
Cut sausages into bite-size pieces, 3/4 to 1 inch; return to pan. Add potatoes to pan.
Lower heat to 350°F. Return pan to oven. Roast 15 minutes, stirring.
Add peppers, onion and garlic to pan. Roast 30 minutes, until vegetables are tender.
Cut loaf of bread in half horizontally. Cut crosswise into sixths, for total of 12 pieces, or 6 sandwiches. Place equal amounts of sausage mixture into each sandwich. Serve hot.