Matzo, or unleavened bread, is considered by many to be the "official" food of Passover, since it commemorates the escape of the Israelites from Egypt they left so quickly, they didn't have time to allow their bread to rise.
Traditionally, matzo is made from one or more of five grains: wheat, barley, spelt, rye and oats. According to Jewish dietary laws, the dough from matzo must be baked within 18 minutes of adding water, or it will begin to rise.
Since wheat, barley, spelt and rye all contain gluten, many gluten-free matzo products on the market are made with certified gluten-free oats. Most people with celiac disease or gluten sensitivity but not all can consume gluten-free oats (if you're not sure how you'll react to oats, only try a small amount at first).
You also can find gluten-free matzo products made with corn and soy instead of gluten-free oats, or you can make your own gluten-free matzo crackers. Here's what gluten-free matzo products are available online or in stores as of March 2012:
Barkat, a gluten-free foods company based in the U.K., makes a gluten-free matzo cracker that's free from milk, eggs, nuts and yeast (of course). The matzos include maize (corn) starch, soy bran, tapioca starch, sugar, salt and palm oil. Barkat gluten-free matzo crackers are available by mail order in the U.S.
Shemura Gluten-Free Oat Matzos are made under rabbinical supervision from certified gluten-free Scottish oats. The company offers both handmade and machine-made oat matzos, and uses a special process to cleanse the oat grains of bitterness during the milling process. The matzos and gluten-free oat matzo meal are available by mail order and in a few stores in the U.S., especially in the New York metropolitan area. If you want to purchase these for Passover, the company advises ordering early, since only a limited quantity is produced each year.
Lakewood Matzo makes two kinds of gluten-free oat-based matzos from certified gluten-free oats in a completely gluten-free environment, according to the company. Lakewood's handmade matzos duplicate the size, shape and texture of the company's handmade gluten grain-based matzo products, while the machine-made matzos are a uniform square matzo product. Both the handmade and the machine-made matzos consist of only certified gluten-free oat flour and water. Lakewood also offers a gluten-free oat-based matzo meal you can use in Passover recipes.
Kedem Food Products began importing Yehuda Gluten-Free Matzo-Style Squares from Israel in 2011, and was surprised by the demand the product quickly sold out, and customers were left scrambling to find it. Because of the huge interest in the product, Kedem says it will ship the gluten-free matzos year-round. The company also has obtained gluten-free certification from the Gluten-Free Certification Organization (GFCO), which requires products to test below 10 parts per million of gluten. Yehuda gluten-free matzo are available in lightly salted, onion and fiber-enriched.
If you'd prefer to make your own oat matzos, this recipe from About.com's Guide to Gluten-Free Cooking should provide you with great matzos to serve at Passover or during the year. They contain certified gluten-free oat flour, almond meal and potato starch, and are free of any corn, rice, bean flour or leavening agents. Since they need to be cooked within 18 minutes of mixing, they only take about 30 minutes total to prepare.