Clean and devein prawns, rinse with cool water, drain and pat dry.
Combine marinade ingredients in a shallow non-reactive pan. Add prawns, marinate for 30 to 40 minutes.
You can grill the prawns if you prefer. To grill place on a medium-hot grill and grill for about 1-2 minutes per side.
Alternately add the butter and olive oil to a 12" skillet, bring to medium-high heat. Add the prawns, saute quickly about 2-3 minutes total. Prawns should be just light pink inside. Don't overcook. Serve with rice and a large salad.