01 - Line an 8x4 inch loaf pan with parchment paper, allowing overhang on sides for easy removal of the finished halva.
02 - Combine sugar and water in a medium saucepan over medium heat. Stir constantly until sugar completely dissolves, then bring to a gentle boil without stirring until thermometer reaches 245°F (soft ball stage).
03 - Whisk tahini, matcha powder, and sea salt in a mixing bowl until completely smooth and uniform in color.
04 - Immediately pour hot syrup into tahini mixture upon reaching temperature. Stir vigorously with wooden spoon for 20-30 seconds until mixture thickens, appears matte, and begins pulling away from bowl edges.
05 - Quickly transfer mixture to prepared pan, smoothing top surface. Cool at room temperature for 10 minutes, then refrigerate minimum 1 hour until completely firm.
06 - Lift halva from pan using parchment overhang. Cut into 12 equal squares and serve immediately or store refrigerated.