To celebrate some landmark birthdays, we headed down to the South End to hit up Sibling Rivalry with a group of six on Saturday. Sibling Rivalry's menu pits two chefs - brothers David and Bob Kinkead - against each other to concoct entrees and appetizers with similar themes. Each of the brothers impressed. The food was great and inventive, the dining room was cool and jovial, and the service was excellent. Everyone approved and had a great time. Especially after enjoying some Blueberry Mojitos from the bar.