Make the dressing: Pulse all ingredients except for the olive oil in a food processor. With the motor running, slowly pour the olive oil through the feed tube until incorporated.
Preheat grill to 400 degrees. Thread shrimp onto skewers and place on a tray or baking sheet. Whisk the olive oil, basil, garlic and red pepper flakes in a small bowl. Brush onto the shrimp and season with salt and pepper. Grill 2-3 minutes on each side. Shrimp should be nice and pink. Remove from grill.
To assemble the salad, divide spinach leaves between 2 salad bowls. Top with tomatoes, feta, olives and shrimp. Drizzle with dressing.
Oven Instructions
For step 2, preheat oven to 400 degrees. Arrange shrimp in a single layer on a baking sheet. Brush with the herb oil and roast 3-4 minutes. Flip and roast another 3-4 on the other side, until shrimp are pink throughout. Remove from oven.
Stove Top Instructions
For step 2, brush the shrimp with herb oil and place in a pan set over medium-high heat. Cook 2-3 minutes and flip. Cook another 2-3 minutes until pink. Remove from heat.