Throw in a few drops of Worcestershire sauce. Had that once at a fancy restaurant. Lemon, butter, and Worcestershire.
I’m using Soy Sauce (see above for recipe) but yeah, right in there.
I usually put Worcestershire in my meats (made a chuck roast for Thanksgiving). Would be very similar to the soy sauce (I almost always grill onion pieces in butter and soy these days).