I feed them on the same thing they're fed on every day! This is because I have a friend in the hobby who comes round everyday, twice in some circumstances, to feed and check my water parameters.
If you don't have someone that knows what they are doing you can always try an auto feeder which can be filled with pellet or flake food and set it to feed a certain amount of times per day. Meaning your neighbour only needs to top up the food if needed and check the other basic things like your auto top up.