Now that autumn has arrived, the summer heat is merely a memory in many parts of the Northern hemisphere, including Japan.

Many Japanese homes have motor-operated or hand-cranked shaved ice machines and buy syrup to make shaved ice during the hot months. As a result, they often have shaved ice syrup left over, taking up space in their refrigerators at this time of year.

If you have syrup for shaved ice or other kinds of colored syrups at home, here's a great idea: why not make Japanese 琥珀糖 kohakutō crystal candy?

On ゆう スイーツ研究家 (yū suītsu kenkyūka | Sweets researcher Yū), a YouTube channel introducing a wide variety of sweets and cooking methods with the motto, "Simple but Delicious," owner Yū introduces just such a recipe!

Here's a video explaining how to make it:

The end result is sparkling, beautiful crystal candy in bright red and yellow colors. In this case, strawberry and lemon syrup were used but you can use any color you have. You can add food coloring to make other colors you need from the basic mix.

In addition to syrup and food dyes, the main ingredients are granulated sugar (brown sugar will alter the color) for the sweetness and agar agar to harden it. You can replace it with gelatin but agar agar is best if you're vegan.

Before you can use the agar agar, which is a seaweed-based hardening agent, it's important to soak it for 12 hours in water, then rinse several times until the seaweed smell is gone. Also, when you're dissolving it on medium heat, you should be careful not to burn it. Mixing it too vigorously will alter the properties, so mix it gently and occasionally with a wooden spoon.

Add only a third of the sugar at first to make sure it's well dissolved, then when the agar agar is clear, add the rest. It may look like a lot of sugar, but that amount is important to create the unique texture of the candy and ensure it is clear inside when it's done.

Each time, it's important to heat gently and stir gently. When the bubbles are very fine, it's done. You may need to experiment a few times before getting it just right.

Once you're done making the mix, pour into containers and leave at room temperature to harden. Scoop out chunks with a tablespoon or large spoon to make imperfect chunks that look better as crystals, or, if you want to make specific shapes, you can use a cookie cutter, but be sure that the cutter molds are tall enough for your agar agar mix. You may need to use a larger container to make the agar agar mix thinner.

Once you've made the pieces, dry them on a cooling rack at room temperature for a day or two until they're done. You'll know they're ready when they're frosted on the outside but beautifully clear and gelatinous inside when you break them open or bite into them.

They can be stored at room temperature.

Since they look like jewels, they make great gifts!

You can also use yellow, purple, and black food dyes to create a special Halloween version or red and green dyes for Christmas. Your imagination is the limit...

If you're interested, why not check out the video and give it a try!