This mini-empire of restaurants and cafeterías would have been cerrado a long time ago if the most basic ingredient to any Cuban, let alone Miamian, repast missed the mark. One could say La Carreta's success is founded on a thimbleful of thick, dark, sweetly bitter coffee. The restaurants are able to consistently produce cafecito that is neither too sweet nor too watery. If you don't cheat on the amount of grounds used for each brew, your customers will happily return. "The secret is to use the best quality coffee and buy the whole bean," explains Felix Jimenez, manager of the chain's flagship Calle Ocho locale. La Carreta buys from different suppliers, primarily Pilon, and grinds the beans fresh each day. Jimenez adds: "The other secret is to use a ceramic cup. This is what gives it the special taste. If you use a paper cup, it won't taste the same." Hmm, there's a certain coffee chain from Seattle that might want to know this.