At the back of Dave Line's book "Brewing Beers Like Those You Buy" is a recipe for making a clone of "San Miguel" that uses a can of Edme Superbrew Lager as the base.
Instead of making the kit up to 40 pints, he reduces the total liquid so that you only make it up to 30 pints. By adding a kilo of Golden Syrup, he produces a lager with an average 5.5%ABV. To balance this out and add a bit of extra flavour and aroma, he also steeps a small amount of Hallertau hops in about a pint of hot water for 10 minutes and adds this liquor as part of the total brewing water.
Many years ago, whilst working in Spain as a holiday rep for one of the large travel companies, I spent nearly 15 months living on little else but San Miguel, so I've decided to make a batch up to see just how it compares.
I put it on yesterday afternoon and set my thermostatic heater to 16°C to give it a lower temperature ferment than I do with my beers and it has started to ferment quite nicely.