Heat 1 tablespoon olive oil and 1/2 tablespoon butter in a large frypan over medium heat. Season scallops with salt and pepper. Place half of the scallops in the frypan without crowding; cook until browned, about 2 to 3 minutes on each side. Remove scallops to a plate. Heat 1 tablespoon olive oil and 1/2 tablespoon butter in the frypan and cook remaining scallops. Remove to plate.
Wipe out frypan and return frypan to medium heat. Pour in wine and boil 1 or 2 minutes, until reduced to about 2 tablespoons. Reduce heat to low and whisk in the remaining 4 tablespoons butter; just softening butter to form a smooth sauce. Stir in salt, lemon zest and tarragon. Pour sauce over scallops.