Can't comment on the street food there in particular, but street food in the tropics is a risk in general. Don't know if you saw a travel doc but they typically hand out pamphlets on what you can and can't eat. It's very restrictive: no uncooked fruits/vegetables, everything needs to be boiled, meat well-done, etc. Obviously, drink only bottled water. I think it's best to go down there assuming you will get sick and to just be prepared for it. Cipro is your friend. Honestly, if you follow doc's recommendations, your trip will be boring because you won't be able to eat anything that actually tastes good. The one suggestion i stuck to religiously was bottled water. I didn't drink anything except coke, water, and champagne. Don't forget to brush your teeth with bottled water too. I was really happy I brought wet wipes though. Seriously.

Have fun. Oh and as always when going to colombia, especially if you're gonna be travelling around between cities, check the travel advisories. Be careful with taxis and don't paint a target on your back by wearing anything too flashy.