If using sheet gelatin, place it in a bowl of cold water to bloom. If using powdered gelatin, combine it with 50 grams of water and 100 grams of orange juice. Let the gelatin bloom for 5 to 10 minutes.

While the gelatin is blooming, place the remaining orange juice, ginger, and red pepper flakes in a pot. Bring to a simmer, remove from the heat and let steep for 10 minutes. Strain the orange juice and return to the pot.

Sprinkle in the agar and mix well with an immersion blender. Bring to a simmer while stirring occasionally. Let simmer for 3 to 5 minutes then remove from the heat.

If using powdered gelatin, whisk in the water-orange juice mixture and let dissolve. If using sheet gelatin, squeeze out the water and add the sheets, whisking them into the agar mixture until they dissolve.

Spoon some of the gel base onto a flat, plastic surface, tipping the surface until the gel evenly coats it. Let the sheet set for a few minutes, and then the gel sheet will be ready to use.