01 - Line an 8x4 inch loaf pan with parchment paper, allowing overhang on all sides for easy removal of the finished halva.
02 - Combine sugar and water in a medium saucepan over medium heat. Stir continuously until sugar completely dissolves. Bring to a gentle boil and cook without stirring until thermometer reaches 245°F (soft ball stage).
03 - In a mixing bowl, whisk tahini, matcha powder, and sea salt until completely smooth and uniformly colored.
04 - Immediately pour the hot syrup into the tahini mixture. Stir vigorously with a wooden spoon for 20-30 seconds until the mixture thickens, becomes matte in appearance, and starts pulling away from the bowl sides.
05 - Quickly scrape the thickened mixture into the prepared loaf pan. Smooth the top surface with an offset spatula or the back of a spoon.
06 - Let cool at room temperature for 10 minutes, then refrigerate for at least 1 hour until completely firm and set.
07 - Lift the halva from the pan using the parchment overhang. Cut into 12 equal squares and serve immediately or store refrigerated.