(based on the wikipedia/bugwood recipe as tested during biochymickal_arts_2013)
Ingredients:
Boil sliced, unpeeled potatoes in distilled water for 30 min.
Filter through cheesecloth, saving effluent
Add Dextrose and Agar
Boil while mixing to dissolve
Autoclave 15 min at 121°C (note: Final pH, 5.6 ± 0.2)