Wondering where to open your next restaurant? An operator could do worse than picking one of the 30 or so cities that are home to an NFL franchise. Football is far and away the country’s most popular sport, and league revenues have been going up and to the right for decades. Chances are that any market strong enough to support a team probably also has the right socioeconomic climate for a restaurant with its sights set on mass appeal. Or at least that’s the thinking at Medium Rare, a no-frills steak and fries chain that plans to follow the NFL with new unit openings. “We don’t have to spend money to figure out what cities work,” said co-founder Mark Bucher. “The NFL took care of that for us.”