What is a recipe for hortacha?

OK - I've just come back from Mexico City and the way they make Horchata (I think this is what you mean) there is:

Rice water, sugar and cinnamon (the rice water can be bought as a powder from the market or by boiling rice and using the cooled water) The three are mixed together into a cold drink - a bit like a milkshake. Oh - and it's absolutely delicious!