Preheat your oven to 350F and line two large baking sheets with parchment paper.
In a medium bowl, whisk together the white rice flour, sweet rice flour, black sesame seeds, white sesame seeds, salt, and garlic powder.
Add the toasted sesame oil, soy sauce, and warm water to the dry ingredients. Stir until a smooth dough forms. The dough should be pliable and slightly tacky but not overly sticky. Let it rest for 5 minutes.
Place the dough between two sheets of parchment paper and roll it out as thin as possible, about 1/16 inch. The thinner the dough, the crispier and more delicate the crackers will be.
Remove the top parchment and score the dough into rectangles or squares. Transfer the bottom parchment directly onto a baking sheet.
Bake for 16 to 20 minutes, rotating the pan halfway through, until the crackers are completely dry, firm, and lightly golden around the edges. Watch carefully during the last few minutes to prevent burning.
Let the crackers cool completely on the baking sheet until they are fully crisp and snappy. Break apart along the scored lines and store in an airtight container.