Take a mixing bowl and mix together olive oil, Dijon mustard, minced garlic, lemon and orange juice, basil, and white wine (optional). Gently add the prawns to this mixture and coat them all over. Cover dish, and let stand for 1 hour to marinate.
Heat your outdoor grill to high heat.
Pierce the prawns with skewers and grill evenly for 3-5 minutes or until pink by turning at least once.
Serve with French bread or on a bed of plain boiled rice.