Step 1

Using a small knife or kitchen shears, butterfly shrimp from tail to base of head, leaving peel and head on; devein.

Step 2

Heat 3 tablespoons oil in a small saucepan over medium heat. Add garlic and pepper flakes; sauté until aromatic, about 30 seconds. Transfer to a medium bowl; stir in Pernod and 1 Tbsp. fennel fronds. Season with salt and pepper. Add prawns; toss to coat. Marinate at room temperature, tossing occasionally, for 30 minutes.

Step 3

Prepare a grill to high heat. Grill prawns, brushing with marinade from bowl, until bright pink and just opaque in center, about 2 minutes per side. Transfer to a plate. Mix sliced fennel bulb and arugula in a large bowl. Drizzle lemon juice and remaining 2 tablespoons oil over; toss to coat. Season with salt and pepper.

Step 4

Arrange salad on a plate. Top with shrimp, garnish with 1 tablespoon chopped fronds.