Using a toothpick, gently spear each strawberry through the stem end until the toothpick is about halfway down the strawberry. Line a baking tray or plate with parchment paper. Set a pastry brush and a dish filled with cool water next to the stove.
Add the sugar to a small, heavy-bottomed saucepan and cover with ¼ cup (60ml) cool water. Set the pan over medium-low heat.
Stirring constantly with a heatproof, silicone spatula, stir until the sugar is completely dissolved in the water. Ensure that the syrup does not come to a boil before the sugar is completely dissolved. If you are worried that the syrup is coming to a boil too quickly, remove it from the heat periodically to prevent it from boiling.
As soon as the sugar syrup begins to simmer, stop stirring. Dip the pastry brush in the dish of water and wash down the sides of the pan, removing any collected sugar crystals. Allow the sugar syrup to boil - never stirring - until a thermometer registers at 300°F (150°C), about 15 minutes (see note 2)
Remove the pan from the heat and allow the sugar syrup to stop bubbling and settle for a minute or two. Then, working quickly, dip each strawberry until it is evenly coated in syrup. Allow to set on the prepared parchment paper until cool until hard - about 5 minutes. Eat within 1 hour of dipping.
Video
Notes
1. I recommend using caster sugar (also known as superfine sugar) rather than granulated sugar as it dissolves more quickly and easily. However, if all you have is granulated, this is not a problem. Just ensure it is completely dissolved before moving onto step 4.2. If you don't have a candy or instant-read thermometer, set a dish of ice water next to your stove. Once the syrup begins to boil, periodically add a few drops of syrup to the ice water to test it's doneness. When the syrup immediately cools to a hard, brittle consistency, it is time to remove it from the heat.