In a large bowl, whisk together the olive oil, vinegar, salt, and pepper until combined. Add the parsley, dill, capers, onion, garlic, lemon zest and lemon juice and red pepper flakes.
Stir until combined.
Add the shrimp to the marinade and toss to coat. Cover the bowl with plastic wrap and refrigerate for at least one hour up to 12 hours. Toss the shrimp in the bowl a couple of times while marinating so that it is evenly marinated.
Remove the shrimp from the bowl with a slotted spoon, leaving behind the marinade. Serve on a glass or stoneware platter and drizzle with extra virgin olive oil and a turn of fresh cracked pepper just before serving.
Notes
You could also use a plastic food storage container to store the marinated shrimp.