Rinse shrimp and set aside. Add oil and butter in large skillet over medium heat.
Cook garlic 1-2 minutes or until softened but not browned. Then, add one at a time allowing 5 minutes cook time between each (in order: wine, onion, lemon). Sample (taste) and add more to taste. If you want a stronger garlic taste, add it after wine.
Cook on very low heat. Saute’ 15-25 minutes until achieving desired taste, then add shrimp. Cook until shrimp are pink and firm (2 minutes if adding raw shrimp, less than 1 minute if adding cooked shrimp). Do not overcook shrimp!
Add chopped parsley and salt and pepper to taste before serving. Garnish with lemon slices and parsley sprigs if desired.
Serves 4 as a main dish or 8 as a first course. Serve with white rice, jasmine rice or angel hair pasta.