Combine the yeast, sugar and warm water in a bowl about twice the size of the mixture and whisk to dissolve the sugar. Let sit for 5-6 minutes (10 if the yeast has been in the fridge) or until it is foamy and doubled in size.
Combine the rice flour, sweet rice flour, tapioca starch, xanthan gum and salt in the bowl of a mixer fitted with a whisk attachment (or just the regular beaters – don’t use a dough hook) and mix to combine.
Add the yeast mixture, eggs, olive oil and vinegar and mix on low to combine. Scrape down the sides of the bowl once. Turn the mixer to high and mix for 3 minutes.
Spray a standard sized muffin tin (or jumbo muffin tin) with gluten-free, non-stick cooking spray or brush with more olive oil. Spoon the batter into the forms and shape with a spatula. Cover with a clean kitchen towel and set in a warm, draft-free place to rise. Let rise for 30 minutes or until doubled in size.
Place a baking pan on the floor of your oven (or on the bottom shelf) and fill it with about an inch of really hot water. Position the rack you are baking the bread on in the middle of the oven. Turn the oven on and preheat to 400 degrees.
Brush the top of the rolls with the melted butter, Earth Balance or more olive oil and bake for about 20 minutes (25 for jumbo sized) or until the rolls are golden brown and sound hollow when tapped. Let cool in the pan for 5 minutes then remove to a wire rack to finish cooling.