Combine water, agar-agar powder, sugar, orange juice, and orange food coloring in a medium saucepan.
Place saucepan on the stove on medium heat. Stir frequently until sugar and agar-agar powder dissolve.
Bring mixture to a boil. Give it a good stir. Turn off stove.
Pour agar-agar mixture into a 7 in x 5 inch tray. Allow it to cool for 10 minutes.
Transfer to the refrigerator and allow agar-agar jelly to set for 1 hour.
Unmold agar-agar jelly and cut into 1 in x ½ in thick pieces using a crinkle cutter.
Arrange pieces of agar-agar jelly on a 15 in x 10 in wire rack. Place a piece of parchment paper on the top.
Allow agar-agar to dry indoors in dry climates or outdoors in the sun until a layer of sugar crust appears. This will take several days, usually between 3 to 4 days. Make sure to cover the agar-agar jelly with a muslin cloth or mesh food screen when drying indoors or outdoors.
Remove from oven and place into air tight containers.