Whisk together olive oil, oregano, lemon juice, tomato paste, garlic, salt and pepper in a small bowl. Place shrimp in a large bowl and pour marinade over the shrimp, tossing to coat.
Marinate for 30 minutes to 2 hours in the refrigerator.
To make the zesty butter sauce:
Melt the butter in a small saucepan over low heat (if the heat is too high, the butter will brown). Add salt, garlic, lemon juice, crushed red pepper, and fresh herbs. Set aside until ready to serve. (Rewarm before serving if necessary.)
To grill the shrimp:
Place wooden skewers in water for at least 30 minutes before threading the shrimp on them to grill.
Preheat grill to medium high.
Grill shrimp on medium high heat for 3-4 minutes per side or until shrimp are done.
Brush warm zesty butter sauce over shrimp and serve.