Butterfly shrimp by making a slit down the back of each from the large end to the tail, cutting to, but not through, the inside curve of shrimp. (Do not peel.) Devein, if desired; set aside.
Pour through a wire-mesh strainer into a bowl, reserving garlic and basil. Return oil to pan.
Add tomato and shrimp; cook over high heat 1 to 3 minutes or until shrimp turn pink. Stir in garlic and basil, if desired.