Step 1Peel, butterfly and devein the shrimp. If rinsed in cold water, blot dry. Dust well with the flour.
Step 2Melt 4 tablespoons of the butter in a skillet over medium heat. Increase the heat to high, add the shrimp and cook until they begin to turn pink, 2 minutes. Immediately add the green onions, mushrooms, basil and salt and pepper to taste. Stir well and cook until the vegetables are slightly softened, 2 minutes. Add the wine and cook until the liquid is reduced by about one-third, about 2 minutes.
Step 3Remove the pan from the heat and stir in the remaining 3 tablespoons of butter, the parsley and the lemon juice. Serve immediately.