How do you get fire ants out of your raised bed?! I went on vacation and came back to a giant mound of ants in my potato box, obviously i don't want to spray anything toxic as they have made their home above my potatoes!

Also do they cause any harm to the tubers or are they ok to eat after the ants are gone?

Non-chemical control of fire ants is the use of boiling water on the mound that can kill as much as 60% of the occupants. The problem with that is that boiling water can of course kill the plant too. If you are confident that you can avoid the potato plant then that is a good approach. Simply pour directly onto the mound. You can do this over successive days to ensure you get them all. Note that those you do not kill will appear elsewhere as they relocate.

You can also shovel the colony into a large container (bin) with talcum powder around the edges (the talc stops them climbing up the side). Also put the talc on your shovel so they dont run up and bite you. But for safety wear gloves also. You can then add soapy water to the mixture to kill them. A cool morning is the best time and a deep shovel to collect as many as possible

Note that there are organic solutions and Some contain citrus oil (dimonene), pyrethrins, rotenone or pine oil (turpentine). But the problem as you recognize is that you are eating the potatoes so I would avoid these solutions.

Fire Ants are dangerous to your physical health and unless they are 100% gone, you are going to have a threat of bites. This is one time when I take liberties. There is a product called Amdro, which is nearly 100% effective in killing fire ants. It is sprinkled at the opening to the nest, and is delay activated, allowing them to carry it to the nest where the queen eats it (and this is key to getting rid of a colony) and dies, along with the rest of the ants. It is not sprayed on the plants. I am aware that this ant bait is then in the soil and I am not sure if you can then call it "organic" but if the organic suggestions tried above do not work, I would use it as a last resort. Fire ants are not something to be messed with, they can cause scarring and allergic reactions in addition to the painful bites.

I don't live in an area that has fire ants, but I've read that molasses (4 tablespoons in a gallon of water) can encourage them to relocate.
http://www.malcolmbeck.com/books/gv_m...
This article suggests adding orange oil and manure tea as well, and they sell a ready-made product containing them.