Men's Vogue has a great piece on the man behind some of Manhattan's best burgers:

If you haven't heard of [Pat] LaFrieda, it may be because you don't own one of Manhattan's better restaurants. He's the third Pat LaFrieda to work at LaFrieda Wholesale Meats (his father, Pat LaFrieda, Jr., still runs the day shift), the supplier for Babbo, Momofuku, BLT Steak, A Voce, the Union Square Cafe, and another 200 establishments. He also grinds the meat for the city's most celebrated hamburgers: Stand, BLT Burger, Shake Shack, and the Spotted Pig all use custom LaFrieda blends that start with chuck and then might (or might not) include sirloin, brisket, boneless short rib, shank, skirt, flat iron, and even hanger. (Brgr's hamburger is ground in Montana.) Each blend is a closely guarded secret, tailored to the techniques and demands of a particular restaurant: Will it be a thin or thick patty? Griddle or grill? Medium or high heat?

After the jump, a breakdown of different burger joints' recipes.

Stand Burger
Recipe: Burger mixture comprises of a custom blend that starts with chuck with the addition of sirloin (each blend is a closely guarded secret)

BLT Burger
Recipe: Burger mixture consists of custom blends that include flat iron

Spotted Pig
Recipe: Burger mixture includes boneless short ribs along with a secret custom blend

Shake Shake
Recipe: Burger mixture includes 25 percent to 30 percent brisket.

Related: My visit to Master Purveyors, another old-school meat outfit in the Bronx