I use:
1/4 cup potato flakes
1/4 cup distilled vinegar
1/4 cup hot water
1 tsp confectioners sugar (I also have used brown sugar)
Mix it in your media container. It should be like a thick paste. If it seems too dry, add a wee bit more water. If too wet, add potato flakes lightly until you get the right consistency.
Sprinkle some yeast on top, add excelsior (or coffee filters), seed the culture and you're off and running.
That recipe gets me about a month's worth of flies once it starts taking off (normally about 2-3 weeks, depending on temps)
Education is the most powerful weapon we can use to change the world ~ Nelson Mandela