WHISK together olive oil, orange juice, Dijon mustard, garlic, parsley, and salt in a small bowl and set aside.
PREHEAT grill or grill pan on the stovetop over medium heat.
THREAD the sliced sausage rounds, pineapple, bell peppers, and onion onto skewers, alternating until the skewer is full. Brush the finished skewers with half of the glaze.
GRILL the skewers for 8-10 minutes, turning halfway and brushing with remaining glaze until sausage is browned and veggies are tender.
SERVE hot and sprinkle with extra fresh parsley (optional).