Ivy
Ivy can be used to make dish soap. Here is the method (that probably needs testing and improving) :
Boil 100g of leaves in 2l of water for 5 to 10 minutes. Let it cool down. Crush the leaves, and let them soak in the juice for another 15 minutes. Collect the juice (press the leaves to get as much product as possible), and use it as dish soap.
Results
* Goes off after a while (2 weeks) and stinks * is in that concentration not very effective, should be more concentrated
Further Steps
* try a higher concentration * research another method * try add antiseptics like cinnamon