Tin of chickpeas (see above)
2 - 4 tbsp finely chopped fresh parsley
2 - 4 tbsp finely chopped fresh coriander
1 teaspoon salt
1/2-1 teaspoon chili powder
4 cloves of garlic
1 teaspoon cumin
1 teaspoon baking powder
4-6 tablespoons flour
Place the drained chickpeas in the bowl of a food processor fitted with a steel blade. Add the parsley, coriander, salt, chili powder, garlic, and cumin. Process until "blended but not pureed." (There is not really enough liquid in this for you to wind up with what I would call a puree.)
The original recipe suggests that you then sprinkle the baking powder and flour in and pulse the food processor to mix it in. I found this really didn't mix it properly -- again possibly because the mixture was not wet enough -- so turned the chickpea mixture out into a bowl and mixed the flour and baking powder in by hand. You are looking to get the mixture to a point where it's more like a dough than a puree -- I found it took more like 6-8 tbsp of flour.
Refrigerate the dough (covered) for several hours.
Form into balls about the size of a table-tennis ball. Normally one fries falafel but I found that baking them worked just as well; about 20 minutes at 180C/gas 4 cooked them through without drying them out too much.