If letting a cleanser & water paste doesn't work, try using some OxyClean.
I did the same thing with a plum/strawberry mix earlier and the cleanser just didn't cut through it. I just made sure the bottom was wet (I filled it with water & then poured out almost all of the water so that it was very damp) and then sprinkled on a scoop of the OxyClean. It bubbled up & after about 20 minutes, I was able to wipe it out with a paper towel.
Kat - the lazy mod who likes things that do the cleaning for her