The egg sandwich showdown: Lawson, 7-Eleven, or Family Mart?Cheryl TehEgg sandwiches are a popular comfort food in Japanese convenience stores, or konbinis.At Family Mart, Lawson, and 7-Eleven, you can get one for less than $2.I, a lover of egg salad sandwiches, set out to rank them on my trip to Tokyo this summer.I've been to Japan over a dozen times and eaten enough convenience store egg salad sandwiches to call myself an authority.I've had th…