Return to the Babylon Club. First of all, to unlock this mission, you have to have 90% turf in Little Havana. You should already have 60% from the fronts you've bought, but to get extra turf complete Felix's leads in Little Havana and wipe out the gangs.
Now as you may or may not have noticed, Tony is feeling a little down and numerous people are cocking guns. Take out the guys in front of you and then get to the kitchen out the back, which holds a medical pack and stops you from being surrounded as they all have to come towards you via one of two passages which meet at the bottom. Hang around there and take out those that come to you. Use blind rage wherever you can to speed up the whole process. After you've taken out most of them, another one will turn up, so shoot him too.