Ever feel like a big, juicy, greasy hamburger doesn’t pack quite big enough of a fat-and-cholesterol punch for you? The line cooks at BLT Burger to the rescue, then. Killing time at the end of a shift one night, the kitchen crew at Laurent Tourondel’s Sixth Avenue outpost threw a burger in the deep fryer to see what would happen. The magnificent result was the King Burger, a five-ounce hunk of ground beef coated, fried, and served on a soft bun with lettuce, tomato, and onion. There’s more to it, and it’s this week’s Sandwich of the Week.