El Colon is the best place to sit after a walk through Merida, and have a sorbet.
We tried the sorbetes de pitaya y de mamey. (Pitaya is called dragonfruit up here) Both were incredibly delicious, with the mamey being sweeter and creamier and the pitaya a bit tart-sweet.
Check out some good pictures of their sorbets on their website:
http://dulceriaysorbeteriacolon.wordpress.com/about/