Step 1

Thread the shrimp onto skewers, if desired. (I usually don't bother, unless the shrimp are on the smaller side, in which case they might slip through the grill grates.)

Step 2

In a food processor or blender, combine the olive oil, basil, garlic, red pepper flakes, salt, Parmigiano-Reggiano and walnuts. Process until the mixture is well blended. Reserve two tablespoons of the pesto in a bowl large enough to hold all of the shrimp and set aside. Pour the remaining pesto over the shrimp and let sit at room temperature for about 30 minutes to marinate.

Step 3

Preheat the grill to medium-high heat. Lightly dip a wad of paper towels in vegetable oil and, using tongs, carefully rub over the grates several times until glossy and coated. Place the shrimp on the grill and cook until plump and slightly charred, a few minutes per side. Transfer the cooked shrimp to the bowl with the reserved pesto and toss to coat evenly. Serve immediately.