Heat the oven to 200°F. Spread the Sriracha in a thin layer on a silpat- (preferably) or parchment-lined baking sheet and place in the oven.
Dehydrate until completely dried, about 1 hour, 20 minutes, depending on thickness. (Note: If using parchment, this will go faster, but you will lose a bit more sauce to the parchment. Try not to let the parchment itself get too dry and brittle or it will be more difficult to crumble off the powder.)
Remove the baking sheet from the oven and set aside to cool at room temperature. Place the cooled Sriracha in a plastic bag and crush until finely ground. Use in tiny amounts as a garnish. (The dehydrated Sriracha is spicier and more intense than liquid Sriracha.)