Instructions? On their website? I missed this.......where was that exactly?
1) You want four main types of flour in your mix--
Bodifiers-- Teff, Sorghum, Rice, bean flours, brown rice, quinoa, millet, amaranth, and cornmeal are a few options. These provide bulk and protein as well as the vitamins (if any, teff is a great source of vitamins).
Modifiers-- Tapioca starch, cornstarch, potato starch, arrowroot powder. These provide lightness and smoothness to the mix.
Moisturizers-- potato starch (this is a duel status item and should be counted in the ratio as a modifier, but if you use too much it will over moisturize the mix), potato flour. These counterbalance the drying tendencies of modifiers.
Extenders-- guar gum, xanthan gum, pectin, (to a degree) fruit acids, and, to a degree, flaxseed. These substitute for gluten and add extra body and stretch to the flour mix, as well as extend the shelf life of your baked goods.
A good ratio to make is 2 cup bodifier: 1 cup modifier: 1/4 cup moisturizer: 3 tsp. extender
You can multiply this ratio for any amount. The secret to getting a mix you like is to mix and match within the categories, but keep the ratios the same.
So you might use 1/2 cup brown rice flour and 1 1/2 cups of teff flour, for a 2 c of a bodifier, etc.
You want to buy or make a mix that has at least 4 g protein in it per1 cup. So what you'd do is take the protein content of each ingredient you used, add them all together, and divide by the number of cups you get (usually 4 c to a pound).
Brown rice has more protein than white. Bean flours contain more protein than grain flours. You need this protein content in order for things like pie crust (and bread) to turn out properly (to fail less).
A lot of times a gluten-free recipe will call for gelatin or extra eggs to provide this protein. If you have enough protein in the flour itself, you can avoid adding extra ingredients.
Extenders... use 1/2 the amount of guar gum in the ratio, or you'll get a laxative effect.
Also, understand that you've got to use SOME guar or xanthan gum. Pectin or ground flaxseed alone won't cut it.
It's even more helpful to cook the flaxseed in a bit of water, to make a gel, and add it into the wet ingredients, if you decide to use it.
If you're buying a flour mix you also want to buy one that already has the extenders in it. Otherwise you're paying a huge mark-up for something you can make yourself for next to nothing. It's the xanthan gum and guar gum that's the costly ingredient and secret to great baking.
Your costly ingredients are (in order of cost): xanthan/guar gums; pectin; potato flour, specialty flours (like teff, sorghum, amaranth). If your mix doesn't contain one of these, once again, you're most likely paying a markup for something you could mix in bulk for yourself, quite cheaply.
Also shop around for different brands of flours. Some are grittier than others. Anything too gritty seems to have a cornmeal taste, no matter what you do.
Finally, my advice is to do a cost analysis of your flour mix. I've found that buying a good mix in bulk is usually equivalent to (at LEAST) or even cheaper than mixing it yourself. This is particularly true if you can buy it directly from the manufacturer.