I'm assuming that at least for those of you in the Eastern U.S. that the several varieties of Sumac are easily identifiable, yes? If not, stop right here and get some good field guides or do some internet research and before you eat anything be positive of what you're consuming. If you're bright enough to get yourself dressed and use a computer then you're intelligent enough to learn to positively identify Sumac. Poison Sumac tends to get all the press leaving its humbler cousins in obscurity, but differentiating between the poison and non-poison varieties is very easy. Smooth Sumac and Staghorn Sumac both have red berries, whereas Poison Sumac has white berries, simple. You can use both the Smooth and the Staghorn varieties pretty interchangeably but you should be aware that the Staghorn has more vitamin C than the Smooth. For this recipe I used Smooth Sumac because it is what was growing at the side of the road, "hey that's Sumac STOP THE TRUCK!" and Mr. G dutifully jumps out and twists off 6 berry clusters for me. Some sort of clippers or trimmers would have made the job easier by the way.
You will need to remove the berries as the stems give a bitter taste if you don't. The outer berries will come off easily but the inner ones don't, you can dehydrate the clusters to make removal easier and to store berries for the Winter. Because Sumac berries are high in vitamin C, higher than oranges even, you should keep plenty in reserve to combat colds this Winter. The Native Americans used Sumac extensively for this purpose.
You then boil 1 quart of water and pour it over 1 cup of berries and allow to steep for 15 minutes. Strain the tea through a cloth to remove all debris, sweeten with up to 1 cup of sugar and enjoy. If you've never imbibed Sumac before go easily at first as some people allegedly have a mild allergic reaction to it. The tea can also be combined with elderberry or red raspberries to make a jelly though I've never tried it.
As an aside, many folks on the survivalist forums recommend on stocking up on Vitamin C, but these people's idea of survival tends to involve generators and fossil fuels etc all in the attempt to maintain their current comsumer lifestyle. Our family's plan tends to center around learning to live without or learning to make our own reasonable substitutes and if you share that philosophy then Sumac meshes in nicely with that.