Prepare the molds by lining a 14 cm frame with plastic wrap or using silicone molds. Ensure they are clean and dry.

Mix yellow pectin with 100 g of granulated sugar in a medium bowl, stirring thoroughly to avoid clumps.

Combine fresh lemon juice, lemon zest, and glucose syrup in a medium saucepan over medium heat, warming until about 40°C (104°F).

Gradually whisk in the pectin-sugar mix until smooth, keeping the heat steady as the mixture thickens.

Slowly add the remaining 200 g of granulated sugar in batches while maintaining a rolling boil, stirring vigorously.

Monitor the temperature with a candy thermometer; remove from heat when it reaches 107°C (224°F) and stir in a tablespoon of lemon juice.

Quickly pour the mixture into prepared molds, smoothing the surface if needed. Allow to cool slightly before setting aside.

Let the filled molds set for at least 2 hours at room temperature, preferably overnight, until firm.

Unmold the candies and cut them into desired shapes. Roll in sanding sugar to prevent sticking.

Store in an airtight container at room temperature, away from humidity. Can be frozen for up to a year.