In a food processor, pulse the garlic, shallots, 1/4 cup oil and sherry vinegar until well incorporated. Add the basil leaves, red pepper flakes, lemon juice, salt, and pepper. Pulse to combine. Remove the mixture from the food processor and add it to a large bowl. Reserve a small amount of marinade in another bowl for finishing the shrimp. Toss the shrimp in the marinade and thread them onto skewers. Heat a grill pan to high and cook the skewers for 2 minutes on each side. Remove them from grill and add them to the bowl with the reserved marinade. Add the fennel, arugula and tomatoes. Toss lightly to evenly coat. Arrange the salad on serving plates and sprinkle with Parmesan.