Dissolve the sugar in warm water and mix in the yeast. Allow it to stand for 10 minutes.
Sift the sweet rice flour, brown rice flour, and tapioca flour into a large bowl or the bowl of a stand mixer.
In a large bowl or the bowl of your stand mixer, combine the sweet rice flour, brown rice flour, tapioca flour, xanthan gum, and baking powder. Whisk until well combined.
Add the yeast, eggs, oil, and apple cider vinegar.
Mix until a sticky dough has formed and add the salt.
Continue mixing until you have a smooth dough that springs back when depressed.
Oil, grease, or nonstick spray an 8 1/2" loaf pan and evenly transfer the dough into the pan.
Cover the dough with oiled plastic wrap and place it in a warm area undisturbed. Allow the dough to rise for an hour or until it has reached just under double its original size.
Preheat your oven to 350°F.
Remove the plastic wrap from your bread.
Bake at 350° for 45 minutes.
After removing the loaf from the oven, transfer it to a wire rack and allow it to cool completely before slicing.
Enjoy your low FODMAP sandwich bread!