Set oven to broil and place top rack so that your lobster tails will be 6”-8” from the top of the oven
In a bowl, mix together parsley, garlic, mustard, salt, pepper, olive oil, and lemon juice
Using kitchen shears, carefully cut up the center of the lobster tail shell, stopping just before you reach the tail. Pull the shell apart and slide your fingers around the tail meat to free it from the shell, stopping before you reach the tail. Gently pull the exposed meat up above the shell, squeeze the shell together beneath the meat, and lay the meat on top of the slit in the shell
Place the lobster tails on a sheet pan or rimmed baking sheet and spoon the herb mixture over each of the tails
Top each lobster tail with approximately 1 teaspoon of butter, and sprinkle a pinch of smoked paprika over each one
Place the pan under the broiler and broil for 1 ¼ minutes per ounce (ex. 4 oz = 5 minutes under the broiler)
Lobster is done when the meat is opaque throughout and slightly firmed up.
Top with additional chopped parsley and a squeeze of lemon