Heat pellet grill to 450°F
Melt butter, with oil in a small saucepan over medium heat, add garlic, sauté until fragrant (4-5 minutes). Add lemon juice, parsley, chives, tarragon, pepper & salt, stir to combine. Remove ½ cup of the sauce for cooking and reserve the rest in the saucepan for serving.
Place diced chouriço in a small dry non-stick frypan and cook over medium heat, stirring occasionally until crisp (5-7 minutes)
Skewer lobster tails lengthways to keep them from curling while cooking. Skewers shrimp to make flipping more efficient.
Place lobster halves, flesh side down, on grill and cook for 2 minutes. Flip lobster over and spoon ½ tablespoon of the butter sauce over each half tail; add the shrimp skewers and brush with butter sauce: add the scallops on the shells and spoon ½ tablespoon of the butter sauce over each scallop (allowing it to pool in the shell) continue grilling 5-8 minutes, flipping the shrimp halfway through and brushing with more butter sauce. Cook until lobster meat is opaque & tender (135°F internal temperature), shrimp shell is a pink color and the meat inside is white/opaque, scallop flesh is milky white or opaque and tender (120°F-125°F internal temperature, as they will continue to cook in the hot butter sauce while plating and serving).
Sprinkle each scallop with ½ tablespoon of crispy chouriço and a little of the fresh herbs.
Serve immediately with warm reserved butter sauce, lemon wedges and chopped herbs.