Spray grill with nonstick spray or brush with vegetable oil to prevent sticking. Preheat on high for about 10 minutes.
In a blender, mix butter, oil, garlic, cilantro, lemon juice and seasoning. Puree into a smooth sauce. When ready to cook, brush both sides of fillets with sauce.
Place wahoo steaks on grill and cook, turning once or twice. Brush more sauce as needed.
Fish is done when it flakes easily (about 5 minutes). Serve with lemon wedges.