Shrimp and Arugula Salad

White balsamic vinegar won't discolor shrimp or bright vegetables. To make something more spicy, replace it with white wine vinegar.
Combine the first 3 ingredients in a large bowl.Preheat a large skillet over medium-high heat. Add 2 tablespoons of oil to the skillet; stir to coat. Add the rosemary, pepper, and garlic to the pan; cook for 2 minutes or until the garlic is tender, stirring constantly. Increase the heat to medium-high. Add the prawns to the pan; saute for 6 minutes or until the prawns are tender. Remove the shrimp mixture from the pan. Add the remaining 1 tablespoon of oil and vinegar to the pan; cook for 15 seconds. Drizzle the arugula with the warm vinegar mixture; stir gently to coat it. Spread the arugula mixture over 4 plates; top with the prawns. Serve immediately.