Shark is one of my most favorite fish. I'm thinking you probably mean Black Tip Shark, rather than Black Tail. Both Black Tip & Mako are the types you're most likely to come across in the market.
Black Tip frequently comes in long thick strips which you can prepare in two different ways. You can simply cut them into chunks, marinate, broil, & serve as what we call "Shark Bites" or do as kebobs; or you can butterfly the strips by cutting them almost, but not quite, through & gently flattening them into steaks.
These "steaks" can be prepared via any recipe for swordfish.
I usually marinate mine briefly in any favorite commercial salad dressing, or my own 1-2-3-4 Marinade for meat & then broil or grill. I also sometimes do them with a light coating of a good Dijon mustard & a sprinkling of chopped herbs, like Tarragon, & then broiling. What's nice about shark is that it tends to stay moister than swordfish when cooked under high heat.
As far as the old "Scallop Ruse" goes, years ago unscrupulous seafood purveyors would stamp out pseudo "scallops" from SKATE wings - not shark. However, now that skate wing is considered a seafood delicacy in it's own right, & is more expensive than scallops, this ruse is no longer found.