1. In a bowl, mix together the olive oil, parsley, lemon juice, garlic, tomato paste, salt, and black pepper.
2. Pour the marinade into a large resealable plastic bag and add the shrimp. Seal, and marinate in the fridge for two hours. Reserve a small amount of marinade for basting later.
3. Pre-heat your grill to a medium-low heat. Thread the shrimp onto skewers, piercing once near the tail and once near the head. Throw away the marinade.
4. Lightly oil your grill grate. Cook the shrimp for 5 minutes per side, or until opaque, basting frequently with the reserved marinade.