You can make sourdough from rice that is really really close to the real thing. The basic recipe is this:

• if you want sourdough you need to make a starter, you can use any normal recipe and replace the flour with rice flour or soaked rice that was then blended.
• soak 500g of glutenous rice for 4-12 hours (the more the better)
• add soaked rice to a high power blender with whatever you want for flavor and texture(ie salt, spices, oil)
• blend while adding water until the blender is able to blend all of the rice properly (will be smooth and probably like a batter, not a dough)
• make sure the temperature is ideal for yeast (blend more to heat it up, let it rest to cool down)
• add yeast/starter and blend shortly just to mix it.
• pour the mixture in a loaf pan (about half way to the top) ideally a silicone one as it bonds strongly, if you are not using silicone I would suggest parchment paper
• sprinkle water on top of the batter and let it rise, if done in a coller temperature(longer time) be sure to sprinkle water every now and again.
• when the batter is close but not yet at the top of the pan, move on to baking.
• sprinkle water on top of the batter again and bake at 170-180c with a pan of boiling water to keep the oven air moist.
• it should be done when it has browned and the inner part has reached at least 98c

Some people that have tried it when I made it didn’t even realize that it is not wheat.