1. Place the shrimp, dried, peeled and deveined in a large bowl.
2. In a food processor combine the cilantro, parsley, garlic, red wine vinegar, salt, pepper and lime juice. Pulse 10 times until the ingredients are well incorporated.
3. Turn the processor on and stream in the olive oil. Let it run for about 30 seconds until it forms a cohesive mixture.
4. Rub the chimichurri marinade over the shrimp, reserving ¼ of the marinade for topping after the skewers are cooked. Coat evenly and put in the fridge to marinate for two hours.
5. While the shrimp are marinating, soak wooden skewers in water for 20 minutes, this will prevent them from burning when you put them on the grill.
6. Assemble the skewers, first with a piece of shrimp, onion, tomato, and alternate until each skewer has 3 shrimp on it.
7. Heat your grill or grill pan on high and cook the skewers about 3 minutes on each side, until the shrimp turn pink and begin to curl.
8. Serve with additional chimichurri and optional yogurt sauce.